Support linking project with rnpm

The postlink script takes care of linking in libc++ and libz. So now the only setup instructions will be: `rnpm link realm`.

Resolves #226

package.json

@@ -47,6 +47,10 @@
     "test": "scripts/test.sh",
     "prepublish": "scripts/prepublish.sh"
   },
+  "dependencies": {
+    "rnpm": "1.5.2",
+    "xcode": "0.8.4"
+  },
   "devDependencies": {
     "babel-eslint": "^6.0.0-beta.6",
     "eslint": "^2.4.0",
@@ -54,6 +58,14 @@
     "jsdoc": "^3.4.0",
     "semver": "^5.1.0"
   },
+  "rnpm": {
+    "commands": {
+      "postlink": "node_modules/realm/scripts/rnpm-postlink.js"
+    },
+    "ios": {
+      "project": "react-native/ios/RealmReact.xcodeproj"
+    }
+  },
   "engines": {
     "node": ">=4"
   }

scripts/.eslintrc.json

@@ -0,0 +1,5 @@
+{
+  "env": {
+    "node": true
+  }
+}

scripts/rnpm-postlink.js

@@ -0,0 +1,37 @@
+#!/usr/bin/env node
+
+'use strict';
+
+var fs = require('fs');
+var rnpm = require('rnpm/src/config');
+var xcode = require('xcode');
+
+// The current working directory should be project root of the app that is linking Realm.
+var config = rnpm.getProjectConfig();
+
+if (config.ios) {
+    var pbxproj = config.ios.pbxprojPath;
+    var project = xcode.project(pbxproj).parseSync();
+    var target = project.getFirstTarget().uuid;
+
+    // Create a Frameworks group if necessary.
+    if (!project.pbxGroupByName('Frameworks')) {
+        var group = project.pbxCreateGroup('Frameworks', '""');
+        var mainGroup = project.getFirstProject().firstProject.mainGroup;
+
+        project.getPBXGroupByKey(mainGroup).children.push({
+            value: group,
+            comment: 'Frameworks',
+        });
+    }
+
+    ['libc++', 'libz'].forEach(function(name) {
+        project.addFramework('usr/lib/' + name + '.tbd', {
+            lastKnownFileType: 'sourcecode.text-based-dylib-definition',
+            sourceTree: 'SDKROOT',
+            target: target,
+        });
+    });
+
+    fs.writeFileSync(pbxproj, project.writeSync());
+}