Merge branch 'master' into feature245

Conflicts:
    controller/apps/nodes/api.py
    controller/apps/nodes/fixtures/nodes.json
    controller/apps/tinc/api.py
Use 'name' as TincHost unicode representation.
Exclude registry-server.cert on Build.match_config
Keep /api/gateways for backwards compatibility

Old node firmware breaks if can't found gateways.
See #245 note-42 for more details.