Grab reference to document.body in bootstrap()

This enables loading this component in <head>, when <body> is not
available yet.
Add jasmine's beforeEach() and waitsFor() to jsHint globals
Make bootstrap() return a Promise
Add e2e test for bootstrap(), tests for CSS class handling

Create a jasmine 2.0 -style test helper to remove boilerplate
and ease up potential migration to jasmine 2.0.
Merge pull request #10 from harriha/bugfix/defer-body-element-fetch

Defer bodyElement fetch to happen in `bootstrap()`, fixes #9