Initial searching patch

New methods:
- search_track
- get_albums_for_artist
- get_tracks_for_album

with supporting utility function url_escape_path and
compatibility function quote_url
Add initial tests
(url_escape_path): Add doctest suggested from PR review
(search_track): Add fuzzy arg and return empty list on exception
Merge "Alternative search musiclibrary" (PR #249) changes

Overwrite soco/core.py with Kenneth Nielsen's approach.
Update tests for changed api

Removed reference to max_items arg.
Update documentation words from PR review

Add missing '+possible'
simplify append from PR review
Convenience spelling
Use *args, **kwargs for wrappers and insert args[0]
Comment use of '701' string for 'No such object' UPnP errors
Python 3.2 hates u'' strings
Merge pull request #246 from dajobe/search-tracks

Searching for music library tracks, finding all artists' albums and artist's album's tracks.