Monkey patch ember-cli's Builder.prototype.build.

This fixes an issue with the ember-cli Builder.prototype.build
implementation for 0.1.3 and 0.1.4. The bug was fixed in
ember-cli/ember-cli#2792 and will be
availabe in 0.1.5.  Once that version is published and in normal
usage this monkey patch can be removed.

index.js

@@ -3,6 +3,48 @@ var path = require('path');
 
 module.exports = {
   name: 'ember-cli-rails-addon',
+
+  /*
+     This fixes an issue with the ember-cli Builder.prototype.build
+     implementation for 0.1.3 and 0.1.4. The bug was fixed in
+     https://github.com/stefanpenner/ember-cli/pull/2792 and will be
+     availabe in 0.1.5.  Once that version is published and in normal
+     usage this monkey patch can be removed.
+   */
+  monkeyPatchBuilderBuild: function() {
+    var emberCLIVersion = this.project.emberCLIVersion();
+
+    var portions = emberCLIVersion.split('.').map(function(input) {
+      return parseInt(input, 10);
+    });
+
+    if (portions[1] === 1 && portions[2] < 5) {
+      var Builder = this.project.require('ember-cli/lib/models/builder');
+
+      // this is the ember-cli implementation as of:
+      // https://github.com/stefanpenner/ember-cli/pull/2792.
+      Builder.prototype.build = function() {
+        var self = this;
+        var args = [];
+        for (var i = 0, l = arguments.length; i < l; i++) {
+          args.push(arguments[i]);
+        }
+
+        return this.processAddonBuildSteps('preBuild')
+           .then(function() {
+             return self.builder.build.apply(self.builder, args);
+           })
+          .then(this.processBuildResult.bind(this))
+          .then(this.processAddonBuildSteps.bind(this, 'postBuild'));
+
+      };
+    }
+  },
+
+  init: function() {
+    this.monkeyPatchBuilderBuild();
+  },
+
   included: function(app) {
     app.options.storeConfigInMeta = false;
     if (process.env.SUPPRESS_JQUERY === 'true') {