test(typeahead): increase coverage of tests

Added more tests to typeahead.

Stats from karma-coverage:

Before:
![screen shot 2013-12-24 at 2 12 27 am](https://f.cloud.github.com/assets/132584/1805487/0d9097a4-6c84-11e3-93df-a3775d50e026.png)

After:
![screen shot 2013-12-24 at 2 10 09 am](https://f.cloud.github.com/assets/132584/1805491/11c9716a-6c84-11e3-84e3-8c83e204db2d.png)

I can't get it to 100% because there's some code that can never be reached:
- typeaheadHighlight will never have a falsey query as an empty string doesn't invoke pop-up