[maven-release-plugin] prepare for next development iteration
Updating the Maven Site plugin version 3.1 -> 3.3

Also removing the stagingSiteURL parameter as we should not need
it for the site:deploy goal
JCLOUDS-549: Fix NPE in LoginCredentials.toString
ServerPredicates to make waiting easier.
Updated service types for OpenStack/Rackspace services
JCLOUDS-505: Remove unused ObjectMD5

The only users of this seem to be
org.jclouds.atmos.blobstore.strategy.FindMD5InUserMetadata and
org.jclouds.azureblob.blobstore.strategy.FindMD5InBlobProperties which
are themselves unused.
JCLOUDS-561: Properly populate the ssh agent connection in the builder methods
JCLOUDS-564. Add ephemeral disks for m3.xlarge and m3.2xlarge sizes