Twisted Deferred errback method takes an Exception instead of a string
support per-interface proxies to avoid conflicts at introspection
on interfaces conflict, create only first method on object proxy
bump version 0.3.0 and update doc
Merge tag 'v0.3.0' into cloudeebus-node

Conflicts:
	README.md
	cloudeebus/cloudeebus.js
	cloudeebus/cloudeebus.py
	doc/dbus-tools/dbus-register.html
	doc/dbus-tools/dbus-send.html
	doc/sample/cloudeebus.html
	setup.py
Use proxy.getInterface API in sample code
bump version 0.3.0