Add local_settings_secrets.py to .gitignore
Don't make an additional embedded query in deleting sync sessions.

Especially as this breaks MySQL.
Don't have a maximum number of syncsession records by default.
Merge pull request #142 from jamalex/fix_syncing

Fixes to deleting older sync sessions
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 branch 'release-0.12.0' of github.com:fle-internal/ka-lite-central into develop
Fix issue with concatenating and displaying lazy translations from API
Fix for #2008: ALLOWED_HOSTS not set.
Fix for closed forms: missing KA-LITE-MOD to Django re-applied.