Lyrics.com backend expect a wrong url scheme

[Kraymer]

Problem

Lyrics.com backend is broken.

$ export BEETS_TEST_LYRICS_SOURCES=1
$ nosetests -s -v test/test_lyrics.py

Led to this problem:

======================================================================
FAIL: Test default backends with songs known to exist in respective databases.
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/flap/Dev/beets/test/test_lyrics.py", line 316, in test_backend_sources_ok
    self.assertFalse(errors)
AssertionError: ['LyricsCom', 'MusiXmatch', 'Genius'] is not false
-------------------- >> begin captured logging << --------------------
[...]
requests.packages.urllib3.connectionpool: DEBUG: Starting new HTTP connection (1): www.lyrics.com
requests.packages.urllib3.connectionpool: DEBUG: http://www.lyrics.com:80 "GET /the-beatles-lyrics-lady-madonna.html HTTP/1.1" 301 20
requests.packages.urllib3.connectionpool: DEBUG: http://www.lyrics.com:80 "GET /lyrics/the%20beatles%20by%20lady%20madonna HTTP/1.1" 200 10372

The song page real url is http://www.lyrics.com/lyric/9853981 whereas the plugin try to fetch http://www.lyrics.com/lyrics/the%20beatles%20by%20lady%20madonna.