#22 Allow to disable versioning

[mpermar]

Currently there is an open issue in Jackrabbit that prevents the system to remove all versions when a versionable node is removed or even when the node is tagged as non versionable. There is more information at http://issues.apache.org/jira/browse/JCR-134

As some repositories could need fast access to documents and would not care about versioning at all, being able to disable versioning in a repository will save space and time making the system more escalable.