Updated online/offline event checks so they are run during initialisation.

Changed the online event to `once` and set it to be bound every time the node goes offline.

The above changes handle the case where:
1) `embark run` runs and starts geth.
2) geth is killed manually
3) `embark blockchain` is run in separate process to restart geth
4) the `embark run` process detects this change and restarts the web3 provider and recompiles/deploys/builds

Every time `embark blochain` is restarted, an error is appended and all are emitted from the `eth-block-tracker`. This is a bug but can't figure out where it originates. The downside is that if, for example, `embark blockchain` is restarted 4 times, there will be 4 errors emitted from the `eth-block-tracker`. Because of this, errors emitted from `eth-block-tracker` have been reduced to trace to avoid clogging the logs.

lib/contracts/provider.js

@@ -0,0 +1,117 @@
+const ProviderEngine = require('embark-web3-provider-engine');
+const RpcSubprovider = require('embark-web3-provider-engine/subproviders/rpc');
+const WsSubprovider = require('embark-web3-provider-engine/subproviders/websocket');
+const async = require('async');
+const AccountParser = require('./accountParser');
+const fundAccount = require('./fundAccount');
+
+const NO_ACCOUNTS = 'noAccounts';
+
+class Provider {
+  constructor(options) {
+    this.web3 = options.web3;
+    this.accountsConfig = options.accountsConfig;
+    this.blockchainConfig = options.blockchainConfig;
+    this.type = options.type;
+    this.web3Endpoint = options.web3Endpoint;
+    this.logger = options.logger;
+    this.isDev = options.isDev;
+    this.engine = new ProviderEngine();
+    this.asyncMethods = {};
+  }
+
+  startWeb3Provider(callback) {
+    const self = this;
+
+    if (this.type === 'rpc') {
+      self.engine.addProvider(new RpcSubprovider({
+        rpcUrl: self.web3Endpoint
+      }));
+    } else if (this.type === 'ws') {
+      self.engine.addProvider(new WsSubprovider({
+        rpcUrl: self.web3Endpoint,
+        origin: this.blockchainConfig.wsOrigins.split(',')[0]
+      }));
+    } else {
+      return callback(__("contracts config error: unknown deployment type %s", this.type));
+    }
+
+
+    // network connectivity error
+    self.engine.on('error', (err) => {
+      // report connectivity errors as trace due to polling
+      self.logger.trace('web3 provider error: ', err);
+      self.logger.trace('stopping web3 provider due to error');
+      
+      // prevent continuous polling errors
+      self.engine.stop();
+    });
+
+    self.engine.start();
+  self.web3.setProvider(self);
+
+    self.accounts = AccountParser.parseAccountsConfig(self.accountsConfig, self.web3, self.logger);
+    self.addresses = [];
+    async.waterfall([
+      function populateWeb3Wallet(next) {
+        if (!self.accounts.length) {
+          return next(NO_ACCOUNTS);
+        }
+        self.accounts.forEach(account => {
+          self.addresses.push(account.address);
+          self.web3.eth.accounts.wallet.add(account);
+        });
+        self.asyncMethods = {
+          eth_accounts: self.eth_accounts.bind(self)
+        };
+        next();
+      }
+    ], function (err) {
+      if (err && err !== NO_ACCOUNTS) {
+        self.logger.error((err));
+      }
+      callback();
+    });
+  }
+
+  fundAccounts(callback) {
+    const self = this;
+    if (!self.accounts.length) {
+      return callback();
+    }
+    if (!self.isDev) {
+      return callback();
+    }
+    async.each(self.accounts, (account, eachCb) => {
+      fundAccount(self.web3, account.address, account.hexBalance, eachCb);
+    }, callback);
+  }
+
+  stop() {
+    this.engine.stop();
+  }
+
+  eth_accounts(payload, cb) {
+    return cb(null, this.addresses);
+  }
+
+  sendAsync(payload, callback) {
+    let method = this.asyncMethods[payload.method];
+    if (method) {
+      return method.call(method, payload, (err, result) => {
+        if (err) {
+          return callback(err);
+        }
+        let response = {'id': payload.id, 'jsonrpc': '2.0', 'result': result};
+        callback(null, response);
+      });
+    }
+    this.engine.sendAsync.apply(this.engine, arguments);
+  }
+
+  send() {
+    return this.engine.send.apply(this.engine, arguments);
+  }
+}
+
+module.exports = Provider;

lib/modules/blockchain_connector/index.js

@@ -160,14 +160,6 @@ class BlockchainConnector {
         if (err && err !== NO_NODE) {
           return cb(err);
         }
-        else if ((statusObj && statusObj.status === 'off') || err === NO_NODE){
-          self.provider.stop();
-          self.events.on('check:backOnline:Ethereum', () => {
-            self.provider.startWeb3Provider(() => {
-              self.logger.trace('web3 provider restarted after ethereum node came back online');
-            });
-          });
-        }
         cb(statusObj);
       });
     }, 5000, 'off');