Refactoring SdnPSSSoapHandler and reading controller URL from config file
Restlet implementation of FloodlightSDNConnector

With these changes, FloodlightSDNConnector is no longer using curl
to send requests to Floodlight. Restlet framework was adopted to
send/receive commands to Floodlight's Static Flow Pusher REST API.

NOTE: this commit depends on these changes to Static Flow Pusher:
https://github.com/hsr/floodlight/commit/f7b5a45bdba505ab1c38c74bd42a5ace392a50f6
For more information, read the commit message on the link above.