Make usage of moment consistent throughout app

This always includes the user's language preference when loading moment.
It also deletes the moment global, so if you don't require it somehow
you will get an error trying to call `moment`'.

This is setup to provide moment to both angular and plain JavaScript
modules. In angular modules, just add `moment` as a dependency. In plain
js use `import moment from 'tower/shared/moment/moment';`.

awx/ui/static/js/system-tracking/date-picker/date-picker.directive.js

@@ -7,8 +7,8 @@
 /* jshint unused: vars */
 
 export default
-    [   '$rootScope',
-        function() {
+    [   'moment',
+        function(moment) {
             return {
                 restrict: 'E',
                 scope: {