Log Message:
0.6 (2016-04-11):
* don't require authentication when getting public collections
* allow submit_ratings() and submit_tags() to submit for all supported entities
* allow 'tags' and 'user-tags' includes on releases
* set the parser when the webservice format is changed
* read the error message from musicbrainz and return it in
  a raised exception
* send authenticaion headers when required
* added get_series_by_id(), search_areas(), search_series()
* updated options for get_releases_by_discid() to support 'media-format'
  and discid-less requests
* parse work attributes
* added various methods to retrieve data from the Cover Art Archive
* added support for pregap tracks
* return 'offset-list' and 'offset-count' for get_releases_by_discid()
* added support for search and browse of events
* added support for 'data-track-list' elements
* added support for get and search instruments
* added support to read all collection types
* added support for search and browse of places
* allow single strings to be used as includes for browse requests
* allow single strings to be used at tag submission
* added support for browse artist by work and work by artist
* added support for 'track-count' elements in 'medium-list's returned by search
* added support to read xml attributes in 'attribute-list' elements