Comment 14 for bug 1070377

As discussed with Mardy on IRC, here is what I suggest to fix this bug:

1) include .provider/service file in the packaging of the purple plugins
2) add a field in .service XML to tell which plugin to use, fallback to use lib<service-name>.so as it does now
3) in empathy stop generating a plugin per protocol, but instead make only one plugin and add the field in all .service files to tell UOA to use that common plugin