test against gnatsd

Signed-off-by: Glenn Oppegard <goppegard@pivotallabs.com>
travis: add go bin dir to $PATH

Signed-off-by: Glenn Oppegard <goppegard@pivotallabs.com>
support for clustered nats

Signed-off-by: Eric Malm <emalm@pivotallabs.com>
Handle StatusNoContent responses appropriately.

When the router received a 204 from an application, it would add a
'Transfer Encoding: chunked' header to the response.  This would cause
some upstream http clients to hang in a read waiting for more data about
the response.

Signed-off-by: Maria Shaldibina <mariash@pivotallabs.com>
Remove old copy of server.go and use the library

The fork of the http server used in the router was missing a fair number
of upstream updates and didn't seem to add additional logic or
capability to the router.  Given the recent issue with 204's it seems
like a good idea to revert to the golang library's net/http
implementation.
Use NATSClient interface