First commit towards a linking move_file().
Now reads config['import']['link'], style fix and default setting added.
Style fixes.
Failing to link a file now throws a FilesystemError.
Merge branch 'master' of https://github.com/sampsyo/beets
Should have corrected some of the style checking errors.
Merge branch 'master' of https://github.com/sampsyo/beets
Merge branch 'master' of https://github.com/sampsyo/beets

Conflicts:
	beets/library.py
Merge pull request #710 from Rovanion/master

Add option to link files instead of moving or copying them.
Docs for link option (#710)
docs: item_linked event (#710)
Hook up `import.link` config option (#710)
Add link parameter to Item.move (#710)