Fix target platform definition

Changing the update site from the integration build to a MS build.

See https://dev.eclipse.org/mhonarc/lists/tycho-dev/msg01192.html

Change-Id: I5abbe77f389e2581876175309f5fc5d5a21b8468
Signed-off-by: Martin Schreiber <m.schreiber@bachmann.info>