Fix for #1957: Use unique URL nicknames to avoid confusion.
Use consistent idioms, remove unused code.
When not on a zone, show the local device only.
Check local device's zone (to avoid issues when Zones exist but DeviceZone does not).
Merge pull request #146 from bcipolli/IDOC-robust

Make control panel more robust for imperfect Device/DeviceZone/Zone setup
Merge commit 'ed5e68d3d3c140a5e420fec616d23acacf8ca7fe' into release-0.12.0

Conflicts:
	ka-lite/kalite/control_panel/templates/control_panel/facility_management.html
Paginate sync sessions.
Merge pull request #144 from bcipolli/1957

Fix for #1957: Use unique URL nicknames to avoid confusion.
Merge pull request #148 from bcipolli/paginate_sync_sessions

Paginate sync sessions.
Merge pull request #2017 from learningequality/ka-lite-central-merge-release-0.12.0

Ka lite central merge release 0.12.0
add integration tests for switching languages
fail fast on database errors
create tests for switching languages
remove redundant integration_tests.py
solve #2016: convert set_user_language to POST data instead of GET
remove unneeded html attributes
implement hack to update csrf token
move i18n testing utility functions to its own mixin subclass
setup a client in I18nTestCase
add test language pack zips and logging statement for langpack download url