selectpicker should refresh itself on changes instead of needing to be told

[myklemykle]

We're using bootstrap-select at my office, and we've hit at least a half-dozen places where we have to jam a special call to selectpicker("refresh") just because we changed some select element. I see many issues reported about this sort of problem here as well.

My question is: why should users of bootstrap-select ever need to call refresh? Why doesn't bootstrap-select use the mutationObserver API to receive an event whenever a relevant change has been made on the select element, and then refresh itself?

We've used this approach with other custom HTML elements in house, and it seems to work.

[caseyjhol]

This will have to wait until v2.0.0 when we are able to drop support for IE < 11.