Tests for prefer_specials

Will ensure prefer_specials is being obeyed correctly.
Support for prefer_specials in SeriesParser

If prefer_specials is True, an entry matching both a normal id type
and special will be flagged as a special. If false, entry will be
flagged as the normal id type.

E.g.: title: the show s03e04 special
prefer_specials = True -> series_id_type: special
prefer_specials = False -> series_id_type: ep
Add prefer_series support to series

Series now accepts an option 'prefer_specials'. If true, entries in
that series which parse as both a normal id type (ep, etc) and a
special will be flagged as specials. If false, they will be flagged as
the normal id type.
prefer_specials support for configure_series

Also allows plugin to accept list of special_ids
List available levels in --loglevel output

Fixes http://flexget.com/ticket/2421
Make some help text a little more dynamic
Rejected command

Rejected command, functions the same as failed. Allows rejected
entries to be listed or cleared.
Reinforce this is only remember_rejected

Remind users that only rejections known by remember_rejected are
listed or cleared.
assume_special support for SeriesParser

Flag which, if true, causes any entries with no IDs found to be
flagged as specials.
Add assume_special support to series

Series now accepts option 'assume_special'. If true, will cause any
entries with no IDs found to be flagged and processed as specials.
Also adds support to configure_series and fixes a typo in
configure_series.
Tests for assume_special
configure_series now sets series options based on the series plugin schema
Merge pull request #196 from tubedogg/develop

Handle error cases better in aria2 plugin
Add --debug-warnings cli flag to raise warnings to errors
Catch raised warnings and print traceback without exiting
Raise all warnings in unit tests
Better debug info for @internet decorator
Make sure api_tvdb is supplying unicode text values, fixes some SQLAlchemy warnings
Merge pull request #199 from tubedogg/develop

aria2 - PEP8 & cli documentation
Catch additional render errors; use correct method of allowing aria2 to set gid.