Binding uninstalls when new nightly is installed

[lipp_markus]

This seems to be expected behavior, as Kai wrote in the announcement.

@Kai

Note 2: The jars are installed in the OSGi cache - which means that they are lost upon an openHAB distro upgrade (which cleans the cache) - you will have to manually re-install then from the marketplace. As the main use case for the start will be for testing pre-releases, I think this is acceptable. For the future, I also plan an improved mechanism, which would download the jars to the addons folder (or something similar), so that they are kept over an upgrade as well.