Small bug fixes

- Delete from Releases when deleting artist/album
- Searcher - Size limits not quite working
- Searcher - 1st newznab used even if disabled
- Rutracker search stopped working for me, fixed by updating Beautiful
Soup. Moved bs4 and html5lib to lib and ensured (I think) it’s imported
from the right place
nzbget - log as info instead of error
Add GNTP library version 1.0.2
Added initial version of Growl notification, including image
Update WebUI to enable/disable Growl notifications
Updated mako lib
Merge with rembo10/develop
Add lib/ folder to the PYTHON_PATH.

This way, modules inside the lib/ folder don't have to be repackaged, and allows top level folders (e.g. bs4) to move to the lib/ folder.

Approach is similar to what CouchPotato does.
Updated imports
Merge remote-tracking branch 'basilfx/growl' into develop
Merged in AdeHub/bugfix - fixed conflict with adding lib folder to path