Move ajax indicator javascript so that it is used for all ajax calls [MJ-324]

Also modified the ajax-busy css so that the indicator appears on top of modals.

There is an error in the javascript tests caused by a missing file. This does not impact the success/failure of the tests. It is already fixed in #201

This and #201 are going to conflict, so I will need to fix merge conflicts in one or the other.

All tests pass.