Added the ability to have multiple JSONs per page

- Moved URL creating for JSON's to Python
- Added basic global JSON for all pages
Merge branch 'autobahn_v1' of https://github.com/Unity-Technologies/buildbot into autobahn_v1

Conflicts:
	master/buildbot/status/web/files/script/project/realtimeRouting.js
	master/buildbot/status/web/step.py
Added global queue, slave usage and build load info