Removed some hardcoded parameters names.
Merge branch 'master' of https://github.com/slipstream/SlipStreamServer

Conflicts:
	jar/src/main/java/com/sixsq/slipstream/connector/local/LocalConnector.java
	jar/src/main/java/com/sixsq/slipstream/connector/openstack/OpenStackConnector.java
	jar/src/main/java/com/sixsq/slipstream/connector/stratuslab/StratusLabConnector.java