FELIX-4460 Prevent misconfigured connector the server from starting

Reorganize startup to setup and start connectors only after having started
the server. If no connector can be started, log a message and stop the
server again to prevent having the HttpService registered without it
actually being able to serve requests.

git-svn-id: https://svn.apache.org/repos/asf/felix/trunk@1579733 13f79535-47bb-0310-9956-ffa450edef68