Plays nicely with Bootstrap dropdowns

Redo how daterangepicker is open/closed, fixing a couple problems.
    
- Allows clicking the trigger button/element to hide the picker (like regular bootstrap dropdowns)
- When a Bootstrap dropdown is open, clicking the daterangepicker element should close/hide the Bootstrap dropdown
- When a daterangepicker is open, clicking a Bootstrap dropdown element should close/hide the daterangepicker.

And I added some test UI to examples.html to make this easy to test.