provide API for setting focus

[lanterndev]

Currently I don't think there's a way to programmatically / declaratively set the focus to a select2 instance on some event or from inside a watch function, so you have to do something like $('#mySelect2').select2('focus', true) where mySelect2 is something like <input type="hidden" id="mySelect2" ui-select2="select2opts" ...>.

[d0coat01]

not sure if they changed select2 or what but to focus select2 it is now:

$('#mySelect2').select2('open');
 //old code $('#mySelect2').select2('focus', true);