Add setting to ignore certain files/paths from scanning

Set ignore_paths to a a '/'-delimited list of values to ignore
certain paths to be not scanned.
Support for author and rating
Add support for sending author and rating information
in the UPNP reply. Needs DB upgrade as there is new column
Too much memory was allocated during xml parsing
Support tv series/episodes, folder metadata

Retrieve metadata from XMBC-based tv series (tvshow.nfo) /episode nfo files.
This includes title, plot, rating, author, director, genre, artists, capture date, season, episode, episode title. This also means we can now set metadata for a folder that is not directly related to a file (e.g. tv show)
All this is presented to the DLNA player, additional entries: upnp:seriesTitle, upnp:episodeNumber
Remove the option of metadata_names as it doesn't make sense anymore. For files always check 'movie.nfo' first, then filename.
Update README

Add features description
Merge branch 'nfo_metadata' into features