Add loading placeholder page while embark is building asset files.

We could extend this further to launch the webserver with the placeholder page before building the contracts as well.

lib/core/fs.js

@@ -19,6 +19,10 @@ function copySync() {
   return fs.copySync.apply(fs.copySync, arguments);
 }
 
+function move(){
+  return fs.move.apply(fs.move, arguments);
+}
+
 function appendFileSync() {
   return fs.appendFileSync.apply(fs.writeFileSync, arguments);
 }
@@ -87,6 +91,7 @@ module.exports = {
   mkdirp,
   copy,
   copySync,
+  move,
   readFile,
   readFileSync,
   appendFileSync,

lib/i18n/locales/en.json

@@ -104,5 +104,6 @@
 	"Ethereum node (version unknown)": "Ethereum node (version unknown)",
 	"No Blockchain node found": "No Blockchain node found",
 	"Couldn't connect to an Ethereum node are you sure it's on?": "Couldn't connect to an Ethereum node are you sure it's on?",
-	"make sure you have an Ethereum node or simulator running. e.g '%s'": "make sure you have an Ethereum node or simulator running. e.g '%s'"
+	"make sure you have an Ethereum node or simulator running. e.g '%s'": "make sure you have an Ethereum node or simulator running. e.g '%s'",
+	"Embark is building, please wait...": "Embark is building, please wait..."
 }