Issue 2016 - Support Patches created with git diff on multiple platforms

Cef patching scripts today only supports patches created using svn on windows. Creating patches with git diff on a different platform adds /dev/null for source/target as for new/deleted files instead of including the same name of the added file.

This patch adds support for patches created with git diff by using the source/target name available when the other one is 'dev/null'. For more details see the original discussion - http://www.magpcss.org/ceforum/viewtopic.php?f=6&t=11284