chore(Grunt): switch from Rake to Grunt

Migrates the Angular project from Rake to Grunt.

Benefits:
- Drops Ruby dependency
- Lowers barrier to entry for contributions from JavaScript ninjas
- Simplifies the Angular project setup and build process
- Adopts industry-standard tools specific to JavaScript projects
- Support building angular.js on Windows platform (really?!? why?!?)

BREAKING CHANGE: Rake is completely replaced by Grunt. Below are the deprecated Rake tasks and their Grunt equivalents:

rake --> grunt
rake package --> grunt package
rake init --> N/A
rake clean --> grunt clean
rake concat_scenario --> grunt build:scenario
rake concat --> grunt build
rake concat_scenario --> grunt build:scenario
rake minify --> grunt minify
rake version --> grunt write:version
rake docs --> grunt docs
rake webserver --> grunt webserver
rake test --> grunt test
rake test:unit --> grunt test:unit
rake test:<jqlite|jquery|modules|e2e> --> grunt test:<jqlite|jquery|modules|end2end|e2e>
rake test[Firefox+Safari] --> grunt test --browsers Firefox,Safari
rake test[Safari] --> grunt test --browsers Safari
rake autotest --> grunt autotest

NOTES:
* For convenience grunt test:e2e starts a webserver for you, while grunt test:end2end doesn't.
  Use grunt test:end2end if you already have the webserver running.
* Removes duplicate entry for Describe.js in the angularScenario section of angularFiles.js
* Updates docs/src/gen-docs.js to use #done intead of the deprecated #end
* Uses grunt-contrib-connect instead of lib/nodeserver (removed)
* Removes nodeserver.sh, travis now uses grunt webserver
* Built and minified files are identical to Rake's output, with the exception of one less
  character for git revisions (using --short) and a couple minor whitespace differences

Closes #199

Conflicts:

	Rakefile

docs/src/reader.js

@@ -7,7 +7,8 @@ exports.collect = collect;
 
 var ngdoc = require('./ngdoc.js'),
     Q = require('qq'),
-    qfs = require('q-fs');
+    qfs = require('q-fs'),
+    PATH = require('path');
 
 var NEW_LINE = /\n\r?/;
 
@@ -43,7 +44,7 @@ function collect() {
        var work2;
        if (file.match(/\.ngdoc$/)) {
          work2 = Q.when(qfs.read(file, 'b'), function(content){
-            var section = '@section ' + file.split('/')[2] + '\n';
+            var section = '@section ' + file.split(PATH.sep)[2] + '\n';
             allDocs.push(new ngdoc.Doc(section + content.toString(),file, 1).parse());
           });
        }