Audiobook support, toggle columns, provider priorities

New Features
NOTE - some of the new features are only available in the bookstrap interface
Eventually plan is to make bookstrap the default for new installs and drop the old default interface

Audiobook support with id3 tag reading
Toggle buttons for column visibility
Combined book searches (rss/tor/nzb all searched in one task)
Provider priorities (prefer nzb over tor, one nzb over another, etc)
Button to clear failed search results (failed search = blacklisted)
Moved libraryscan buttons into Author, eBook and Audiobook pages to only scan relevant parts
Added temporary provider blacklist to stop querying providers that returned an earlier error, eg api limit exceeded, provider unavailable
Removed googlebooks api key, the daily limits are quite restrictive so each user needs to get their own key

Bug Fixes
Better exception handling
More debug messages added
Fix for default interface failing to save config items that only bookstrap interface knows about
Fix missing labels on default config page preventing git items and webroot saving properly
Update from command line moved earlier in bootup, so can recover from previous broken update
Renamed Search Filter to Result Filter so it's more clearly not a search box
More unicode conversions and error trapping