bump to version 0.90 and ensure we're parallel installable with 0.9

bump to version 0.90 and ensure we're parallel installable with 0.9

This is the first move towards 1.0; also

 - kill the config file
 - merge libpolkit and libpolkit-dbus

Now to write a system daemon that libpolkit will use for the
backend. Expect HEAD to be broken for a few weeks at least.

Also see http://ometer.com/parallel.html for what "parallel
installable" means. As a result, all the binaries, man pages, .policy
file dir and so forth have been renamed too. I expect the API to
change a bit. So some (not much though) porting to PolicyKit 1.0 will
be required by current users.