Added an error handling for connection refused to API server.

Change-Id: I4eb640e3072f880491438985872daae425e3296d
Merge branch 'dev/tomohiko/mn-718/20131031' of https://github.com/midokura/python-midonetclient into dev/tomohiko/mn-718/20131031

Conflicts:
	src/bin/midonet-cli

Change-Id: I9b966fd8574bea658e1e679e37bea8c25c6bebbc