Added API access for AngularFire version number

Author: jwngr

src/utils.js

@@ -432,6 +432,12 @@
             });
             return dat;
           },
+
+          /**
+           * AngularFire version number.
+           */
+          VERSION: '0.0.0',
+
           batchDelay: firebaseBatchDelay,
           allPromises: $q.all.bind($q)
         };