Merge pull request #1038 from waven/discstub

Disc stubs: Display information that a optical disc drive is needed if a disc stub is selected on a system without any optical disc drive

diff --cc language/English/strings.po
Simple merge

diff --cc xbmc/Application.cpp
Simple merge

diff --cc xbmc/storage/MediaManager.cpp
Simple merge

diff --cc xbmc/storage/MediaManager.h
Simple merge