AMD: Defines Dexter.fakeXHR in AMD

Ref gh-19
Merge pull request #21 from leobalter/19-amd-fix

AMD: Defines Dexter.fakeXHR in AMD
Tests: Node tests now reuse QUnit tests, replacing nodeunit

Fixes #18
Adds browserstack config file (no private keys inside)
README: Remove version info and update browser support