Add support for artist aliases

Use MusicBrainz artist aliases to import files with artist names in an
appriorate locale
Merge pull request #102 from samdoshi/aliases

Add support for artist aliases (fixes GC-354)
refactor alias discovery into function (#102)
change option name to "languages"; docs (#102)
link to GitHub Issues
import.detail config option (GC-263)
add --flat option to import command (GC-202)
tag_album does not take timid as an argument

see SHA: 75d43270e881a7ecf16de4474b5fec54722ebf2e
go to next locale if no match in _preferred_alias

we should continue here rather than return so that we continue to search
for matches
add unit tests for aliases (#102)
Merge pull request #104 from samdoshi/initial_lookup_fix

tag_album does not take timid as an argument
changelog/thanks for #104
Merge pull request #105 from samdoshi/aliases

Unit tests and bug fix for aliases (#102)
convert: add missing syspath call (closes #106)
format None values as the empty string

Fix due to @pscn. Includes test. Closes #108.
fix bytes literals causing a Unidecode warning

This would trigger a warning in Unidecode when metadata was missing (which is
the only case when those empty-string literals are used). Closes #109, which
is a different fix for the same problem.
mbcollection: human-readable MB exceptions

Fixes #107 by wrapping the API invocation function with exception handlers.
convert: add missing util.displayable_path
initial version of the mbsync plugin

this plugin provides a faster way to query new metadata from
musicbrainz. (instead of having to 're-import' the files)
Currently it lacks all forms of documentation and will only work for
album queries. not really tested so far so be careful
mbsync: write metadata to files...