Exportv4 cs mongodb into es

I'd like to see this phrased as a normal doc comment.

Say:

	// ElasticSearchTestPackage starts an elastic-search server or connects
	// to an existing one and then calls the given function with t as
	// its argument. Its behaviour is dependent on the value of the
	// JUJU_TEST_ELASTICSEARCH environment variable, which
	// can be "none" (do not start or connect to a server), empty 
	// (start a new server) or ip-addr:port holding the address and
	// port of the server to connect to.
	//
	// For example:
	//     JUJU_TEST_ELASTICSEARCH=localhost:9200 go test
?