stefek99 - example (it is also a potential bug report)
'Obvious' fix - I attaching on("key_entered") only once! (not each time when updating query)
Merge branch 'master' into pr/28
Made queryBuilder example production-ready

- Changed Firebase include to use the Firebase CDN
- Changed link to Firebase at the top to be more constant with our
other examples
- Added queryBuilder to gulp so it get’s updated version of the library
- Add queryBuilder to our examples page
- Added “contributed by” attribution at the top
- Cleaned up some code and wording
Updated queryBuilder example to v3
Merge pull request #34 from firebase/pr/28

Updated pull request #28 to make it production ready