[GEOS-6789] Add support for Advertised and Transient parameters in GWC
Merge pull request #846 from Geodan/GEOS-6688-2

[GEOS-6688] Addition to support more interpolation types.
Merge pull request #835 from n-lagomarsini/GEOS-6789

[GEOS-6789] Add support for Advertised and Transient parameter in GWC
Ensuring importer doesn't create illegal layer names.
Merge pull request #828 from jdeolive/importer-legalnames

Ensuring importer doesn't create illegal layer names.
Avoid NPE's in JDBCConfig when an object was deleted by another thread and it tries to return it out of the ids list