[BUGFIX] inaccurate series used
[BUGFIX] inaccurate series used

This fixes the error when:

1. multiple matches are found. This is due to a series Hash being passed in to
   add_tracks, hence, a fuzzy search is done to the raw_name rather than an
   exact match.
2. no series associated to the tracks when series is added for the first time.
   To fix this, the returned object from add_series method is passed into
   add_tracks as the series to be associated.

NigoroJr/viva,NigoroJr/viva