activated url endpoints for downloading updates
properly sort version numbers instead of depending on alphanumeric sorting
Merge branch 'develop' of github.com:fle-internal/ka-lite-central into develop
sort available version updates by version release dates
bring back @api_handle_error_with_json
use builtin datetime.strptime to convert string to date
Merge pull request #136 from aronasorman/1977

Sort available version updates by release date
fix html
Merge pull request #137 from mauk81/develop

fix html
Merge branch 'release-0.12.0' of github.com:fle-internal/ka-lite-central into develop

Conflicts:
	centralserver/central/templates/central/org_management.html
Move POT_PATH to __init__.py file so it can be shared, and rename to POT_DIRPATH for consistency.
Fix for #1919: auto-insert translator comment for any translation containing a format string.
Implement test to make sure translation strings are properly commented.
Adding test case for pot creation and comment-checking.
Basic code for doing deletion stubs locally.  Will not propagate remotely.
Removing is_deletable code.
Remove need for add_syncing_models
Introduce (debug) settings to allow deletions and viewing of deleted objects.
Introduce all_objects manager, which will always return deleted (and not-deleted) objects.
Work-around for validation issue on save, where deleted foreign keys can't be found (they're hidden!)