Update doc/sources/installation/installation-linux.rst

First changes for the linux installation guide. More instructions will be added later!
Update doc/sources/installation/installation-linux.rst

Added Debian and removed Python-OpenGL as dep
Update doc/sources/installation/installation-linux.rst

just cleaned up one thing...
Merge branch 'master' of git://github.com/kivy/kivy

Conflicts:
	doc/sources/installation/installation-linux.rst
cleaned install-linux from merge - hopefully :/
Merge pull request #918 from thopiekar/master

first major update of the linux installation page