Autodetect strip parameter for the patch operation

Some patches require an other option than p0. This one will auto detect the right one. ;)
I took the idea for that from here: http://blog.dustinkirkland.com/2011/03/bikeshed-apply-patch-auto-detect-strip.html So if there is a package for that in the official repo of ubuntu which does it the same way, it should be quite save.