Add members to a SKOS Collection.
Deprecated expand_concept and introduced expand.

The expand_concept method is now deprecated and should be replaced by
expand. All calls to expand_concept are routed to expand by default. The
implementation for expand works for both concepts and collections.
Make unittest more portable.
Added a dict_to_note function.

Added a dict_to_note function in the same vein as dict_to_label. Also
added unit tests for both.
Added a dict_dumper to skosprovider.utils.

Added a utility function to dump a provider to a dictionary. This
enables taking a local copy of a provider.