Do not crash if track cannot be indexed.

FIX: #18, #14
Move if outisde try/except block
Merge pull request #21 from bmihelac/fix-14-no-crash-on-indexing

Do not crash if track cannot be indexed.
FIX: #19 - Error in indexer when using lastfm
Merge pull request #20 from bmihelac/fix-19-lastfm-indexing

FIX: #19 - Error in indexer when using lastfm
Fixed a little bug, now server responds 404 instead 500 when
you try to download an inexistent resource.
Merge pull request #44 from IagoLast/master

Server responds 404 instead 500 when you try to download a nonexistent resource.
Added Mozilla Hacks' article about Shiva
Typos in documentation
Added /about resource
MediaDir objects check existence of paths
PEP8 and some cosmetic changes
Renamed VERSION to __version__
Added contributors list to /about resource
Added subtitle to Clients
Added Shiva4J client
Client authors are now lists
Applying the pokemon pattern
Changed Shiva4J author
Removed unused properties