Select2

Created a new PR for select2 functionality. This PR has new changes with respect to previous PR that was created before. Link for new PR is given below. Current chages was made by passing original name of the element instead of the fake name of the autogenerated select2 element to select2 function. Also made changes for select2 invocation in other files.

Old PR link : https://github.com/civicrm/civicrm-core/pull/2717