Add observeEvent and eventReactive functions
Refactor for code review feedback
Merge remote-tracking branch 'origin/feature/event-reactives'

Conflicts:
	inst/tests/test-reactivity.r
Switch from Bootstrap 2 to 3
Update tab shown/hidden events for Bootstrap 3
Fix appearance of inputs
Update tests for new DOM structure of choices
Correctly find checkboxes and radio buttons with Bootstrap 3
Update selectize's CSS to use Bootstrap 3
Fix appearance of date inputs
Wrap inputs in div with class 'form-group' to maintain bottom margin
Adjust CSS for slider and selectize

This makes sliders and selectize inputs have width 100%, just like other
inputs with Bootstrap 3.
Reduce spacing above sliders
Fix headerPanel spacing

The titlepanel spacing also is unnecessary now with Bootstrap 3.
Update slider animation buttons for Bootstrap 3
Update showcase CSS classes for Bootstrap 3
Set width of divs inside of flowLayout
Fix inline checkboxGroupInputs and radioButtons
Re-document
Update NEWS