Fixes and tweaks to make tests work with babelized code

* Use mocha, chai & sinon from the npm. As of sinon 2.0
  sinon-as-promised is no longer required so it is removed
* Tweak code to re-use the same loader with the same environment
  throghout the code
* Introduce browserify step for testing tools that only provide
  node-compatible libraries (sinon, chai-as-promised)
* Introduce copy step for test data to resolve multiple issues with
  tests depending on files not being symlinks
* Re-introduce custom implementation of setTimeout to resolve issues
  with few tests
* Re-introduce custom Bluebird Promises config & monkey patch

test/content/support.js

@@ -1,3 +1,5 @@
+chai.use(chaiAsPromised);
+
 // Useful "constants"
 var sqlDateTimeRe = /^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}$/;
 var isoDateTimeRe = /^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}Z$/;