bus: fix pattern matching

bus: fix pattern matching

DBus-spec defines two different pattern matchings:

  1) Path and namespace prefix matching. In this case, A matches B either
     if both are equal, or if B is fully included in the namespace of A.
     In other words, A has to be a prefix of B, but end with a separator
     character (or the following character in B must be one).

     This is used for path_namespace= and arg0namespace=

  2) The other pattern matching is used for arg0path= which does a two-way
     matching. That is, A must be a prefix of B, or B a prefix of A.
     Furthermore, the prefix must end with a separator.

Fix the sd-bus helpers to reflect that. The 'simple_' and 'complex_'
prefixes don't make any sense now, but.. eh..