Fix for TbSelect2

In version 3.4.1 of select2 method "enable" returns "true".
When using "disabled" property and events this widget generate js code like this "jQuery('#selector').select2({options}).select2('enable', false).on('change', ...)"
which throw js error because of .select2('enable', false) returns boolean instead of object.
BUT! This fix only allow to set one of two property in one time.
Merge pull request #752 from pelmennoteam/master

Fix for TbSelect2