Added Discogs search plugin.
Add a lyrics backend that scraps results from google custom search api.

Add a 'fallback' option to facilitate working around the 100 queries/day google
limit by marking files as 'visited' so they are not considered for lyrics search
on the next beet run.
I've put my own google_engine_ID as default value in the code but could be
reconsidered, this engine contains databases known to be scrappable by the
plugin algorithm though.
lyrics: restore tags write and fix extract_text()
- changes to mediafile.py. Provides a delete method which allows the user
  to remove all audio metadata from the mutagen call "delete"

  example : mediafileobject.delete()
Update dependency to latest mutagen version

Mutagen 0.20 has a bug when querying bitrate of Musepack files. Let's make life
easier on everyone and make sure they have up to date version. As a bonus
mediafile tests don't fail with 0.21
Fix python namespaces for test runs

We need to make sure we don't use namespaced versions that are already installed
on the system but rather use local version from current sources
fix VFS tests

The configuration was not loaded for these tests because they didn't inherit
the common test harness. These failures were hidden on my system because of
some kind of dependency on another test.
Merge pull request #245 from sochotnicky/master

Update mutagen dependency to 0.21
Merge pull request #244 from jesseward/delete-metadata-mediafile

- changes to mediafile.py. Provides a delete method which allows the user to clear current metadata information...
mediafile: delete() works with ASF (#244)
Code style + fix doc typo
hard limit on guessed filename length
Compute Content-Length to make tracks seekable in most players via the web plugin
Merge pull request #246 from xhochy/feature/add-content-length-header

Compute Content-Length to make tracks seekable in most players via the web plugin
merge
changelog for #246
lastgenre: fix crash with canonicalization
Merge pull request #243 from KraYmer/master

Add a lyrics backend that scrapes results from google custom search api
misc. style cleanup for #243
docs and changelog for #243

Also note that this fixes #162.