Add blur/focus event triggerings (#798)

An attempt to add blur/focus events.  Related to issue #798

I ran in to problems using the real 'blur' and 'focus' events, so I simplified the problem by using 'select2:blur' and 'select2:focus.'

Also, when switching between the `container` and `search`, a blur and focus event are emitted.  I'd like to avoid that, if possible, but I'm not sure how to, and it's late.