Add `--config` cli option
Make --config path absolute
coveralls: attempt to exclude non-beets code
coveralls: another attempt at narrowing coverage

perplexingly, the previous way was segfaulting on travis
coverage: exclude some code

Don't report on the test suite itself or on a few obviously excludable lines.
Fix #514: add distance between string and None
fromfilename: fix #460: crash w/ no capture groups
fix typo in BytesQuery
fix mpdstats plugin after query restructuring

BytesQuery does not handle unicode strings correctly at the moment
and PathQuery seems like a reasonable query to use.
Merge pull request #516 from kljohann/typo

fix typo in BytesQuery
fix #517: BytesQuery accepts unicode strings
Merge pull request #515 from kljohann/mpdstats

fix mpdstats plugin after query restructuring
tiny option-choosing fixes for #518

* 'L' check needs to be lower-case
* letter for 'More candidates' is M, not C
a bit more docs, changelog for #518
Rename `as aLbums` option (#518)
Add pull() generator to Pipeline
Use Pipline.push() in importer stages
Add `group albums` stage and configuration
Remove duplicate code
Add `--group-albums` cli option