Added fmt() function and switched to using it (#1376)

Also changed the top of a few modules to match PEP 8.
Changed a couple more strings to use fmt()
Fix for auto-saving backups (#1392)
fixed typo (#1392)
Merge branch 'staging' into gh-1376
Fixed calling params when leaving a team (#1376)
Removed unused exception class

It had an old-style format string and I figured it was better to
remove the cruft then try to fix it.
Added filter to select language of team members to send message to
Fixes issues in message filtering:\nIgnore message author when querrying team languages\nDisable language selector if messaging single user
Do not filter languages, display all of them
Fixing issues with no language selected for issue #831
selenium tests for the team messaging functionality
Merge pull request #1403 from pculture/gh-1376

Gh 1376
improve implementation of language list retrieval, as part of issue #831
Merge branch 'gh-831' of github.com:pculture/unisubs into gh-831
Merge pull request #1405 from pculture/gh-831

Gh 831
Send messages to team as a bulk, for issue 1408
One more fix for autobackups (#1392)
Merge pull request #1413 from pculture/gh-1392

Gh 1392
Improvements in efficiency of bulk messages