added: POC mp4 movie/episode tag support

Backport from @notspiff

This adds basic mp4 embedded meta reading see http://forum.xbmc.org/showthread.php?tid=192982

any code changes will require a knowledgeable person guidance, Im just "the enterprising individual" putting this forward.

I can handle the git portions just fine.
Should we perhaps "hide" the strings here under a define, they are a bit unreadable as is. I guess the variable on the lhs kindof states what it is anyways, so no strong opinion on my end.