Form submission and first item highlighted options + better UX

Solution for issues #1298 and #908

- Added typeahead-auto-highlight option for typeahead (default to true, meaning the first matching item is automatically activated)
- Added typeahead-prevent-submission option for blocking enter event on input field (default to true)
- Better UX: when option auto highlight is set to false, I had to modify few areas of the code to prevent bad behaviour with tab key events.
- Removed click event not needed anymore (everything is done in 'blur') and $document reference