Correct executable bit for source files

Many media files and source code files were marked as executable in Git.
Remove those.

Also a shell script and python script were not marked as executable.

Change-Id: Ieb51bafb46c895a21d2e83696f5a901ba752b2c5
Signed-off-by: Chirayu Desai <cdesai@cyanogenmod.org>