use angular_callbacks_x as jsonp callback function name instead of angular.callbacks.x.

This is because some jsonp backend doesn't allow the callback function name contains '.'
let deferred object's finally method has an alias name 'always'.

'finally' is a reserved word in ECMAScript, we should avoid use it.
temporary disable fetching previousVersions.

It will block grunt till the the remote information back. If the networking is bad, it will block forever, which is very bad. This information is never used at all. see /Gruntfile.js.