UPDATE: p-cdn.com reference added to fix abrupt playlist exits

* adds p-cdn.com as an alternate source URL for songs
* fixes abrupt exits from the addon when song source changes
UPDATE: update to most recent upstream 'pithos'

* 'pithos' updated from repo [2b35f36b91 on 2013-12-19]
* minor changes to script to correspond to newest 'pithos' API

* NOTE: 'pithos' repo @ https://github.com/pithos/pithos
RELEASE: add p-cdn.com as a source URL; update 'pithos'

* v2.1.2

* uses Pandora JSON API (modified code from the Pithos Project)

* BUGFIX: added p-cdn.com as a song source fixing abrupt exits
* UPDATE: 'pithos' update with minor corresponding changes

* BUG: scrobbling broken
* BUG: visualization broken ??

NOTE: see http://forum.xbmc.org/showthread.php?tid=70471
NOTE: Pithos project home @ https://github.com/kevinmehall/pithos

Unfortunately, the JSON API still does NOT have duration information for the
playlist songs, so scrobbling is now broken again, although the player
ultimately shows the correct duration bar while playing the songs.

Visualization seems to be working again... was there an XBMC patch?

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Merge branch 'prelim'