Add recommended Anidb complains about _bsddb

[udochrist]

Describe the bug
No recommended shows from anidb are loaded

To Reproduce
Steps to reproduce the behavior:
Add recommended-> anidb

Expected behavior
List of recommendations

Screenshots
If applicable

Medusa (please complete the following information):
Medusa 0.2.9 on alpine docker

Logs:

2018-09-07 03:15:08 WARNING  Thread_4 :: [db3d9d7] Could not parse AniDB show, with exception: Traceback (most recent call last):
  File "/app/medusa/medusa/show/recommendations/anidb.py", line 91, in fetch_popular_shows
    recommended_show = self._create_recommended_show(show, storage_key=b'anidb_{0}'.format(show.aid))
  File "/app/medusa/ext/dogpile/cache/region.py", line 1270, in decorate
    should_cache_fn)
  File "/app/medusa/ext/dogpile/cache/region.py", line 864, in get_or_create
    async_creator) as value:
  File "/app/medusa/ext/dogpile/lock.py", line 186, in __enter__
    return self._enter()
  File "/app/medusa/ext/dogpile/lock.py", line 86, in _enter
    value = value_fn()
  File "/app/medusa/ext/dogpile/cache/region.py", line 819, in get_value
    value = self.backend.get(key)
  File "/app/medusa/ext/dogpile/cache/backends/file.py", line 220, in get
    with self._dbm_file(False) as dbm:
  File "/usr/lib/python2.7/contextlib.py", line 17, in __enter__
    return self.gen.next()
  File "/app/medusa/ext/dogpile/cache/backends/file.py", line 215, in _dbm_file
    "w" if write else "r")
  File "/usr/lib/python2.7/anydbm.py", line 84, in open
    mod = __import__(result)
  File "/usr/lib/python2.7/dbhash.py", line 7, in <module>
    import bsddb
  File "/usr/lib/python2.7/bsddb/__init__.py", line 67, in <module>
    import _bsddb
ImportError: No module named _bsddb

Additional context
N/a