test(typeahead): add tests for selectMode option

Conflicts:
	src/typeahead/test/typeahead.spec.js
test(typeahead): add tests for keypress handling

Conflicts:
	src/typeahead/test/typeahead.spec.js
chore(docs): add ngOptions & selectMode descriptions to typeahead
fix(typeahead): fix some cases where list would not close on selection click

remove $$postDigest from select callback
also removed some redundant code