Update gstreamer-sharp to 1.4

Removed all native gstreamer libraries from the gstreamer directory. The implementation reads the environment variables from the gstreamer packages to add the gstreamer binaries to the PATH.
The installer can embed the merge module files from gstreamer.
Merge branch 'develop' of https://github.com/xDarkice/Vocaluxe into develop
Update installer. Add gstreamer-installer-files manually (don't want to blow up repository)