[WFCORE-253] Enable the use of expressions for sasl-protocol and server-name.
[WFCORE-256] Remove comment saying Kerberos is only for HTTP.
[WFCORE-257] Remove TODO comment to add access constraints as these attributes are already contained within resources flagged as being MANAGEMENT_INTERFACES.
Merge pull request #335 from darranl/WFCORE-257

[WFCORE-257] Remove TODO comment to add access constraints
Merge pull request #333 from darranl/WFCORE-256

[WFCORE-256] Remove comment saying Kerberos is only for HTTP.
Merge pull request #332 from darranl/WFCORE-253

[WFCORE-253] Enable the use of expressions for sasl-protocol and server-name
[WFCORE-213] :  Clean unreferenced items from the content repository

Now we are using ContentReference to track contents in the content repository.
Now we are tracking references to overlays.
Trying to use server group definition for domain mode.
Simplifying ContentReference
WFCORE-211: Fixing overzealous cleaning of HC content.
[WFCORE-178] :  ContentRepositoryImpl should not call File.deleteOnExit when deleting content.

Using the new Path API instead of File.
Cleaning empty old directories.
Merge pull request #284 from ehsavoie/WFCORE-213

[WFCORE-213] :  Clean unreferenced items from the content repository