Metacat

Add metacatinaccessible exception for query.

Implemented the 'read' API call. Some more to go...

Wrote the login() function, the first of the series of API calls for
the metacat client to be implemented. Also wrote a test class to
test the API functionality.

Added a new subpackage (edu.ucsb.nceas.metacat.client) which is a client
access library for the metacat. There is an interface (Metacat.java) that
provides simple access methods for the main metacat functions. This is to
support clients like Morpho and others that want to programatically access...