docs(README): add installation instructions
fix(typeahead): stop keydown event propagation when ESC pressed to discard matches

Closes #243
fix(tabs): remove superfluous href from tabs template
- Added an ieshiv.js (for now handcrafted) to the demo-assets
- Included in the demo-template.html a polyfill and ieshiv.js for IE < 9
Merge branch 'master' of https://github.com/angular-ui/bootstrap into ie8-compatibility