Document GeoServer naming restrictions wrt ingesting data

[ScottEvil]

GeoServer imposes restrictions on naming conventions and this has impact on namespace names. We need to document this so that GeoWave users & developers can understand the impacts of this.

This issue stems from the thread in: Issue #83

[rfecher]

This related to #664

[datasedai]

I think that the original issue, #83, really related to the gwNamespace, not the GeoServer namespace. If i make a gwNamespace with an invalid value, then accumulo will not be able to create the table. I'm not sure how we missed this during the scrub, but I recommend we update the description of this task to reflect.

I also recommend that we explicitly include in documentation definitions of the different namespaces.
gwNamespace vs. Accumulo namespace
gwNamespace vs. feature namespace