Minor Live Development stylesheet/unit test bugs

This fixes three related Live Development stylesheet bugs: 

1. Stylesheets were loaded asynchronously on initialization. This is a minor issue, but initialization should probably not complete until Live Development is actually initialized. (Things like this tend to cause problems with testing.)

2. The XHR that loaded the .less file was failing due to path problems in the unit tests.

3. The LESS parser was not loaded in the unit test window, so even if the .less files were properly loaded, they would fail to parse. 

This pull request uses require.js instead of an XHR to load the .less file properly, and also adds the less parser to SpecRunner.html so that it is available during unit tests.