made gometa go get installable

go get github.com/couchbase/gometa/cmd/gometa now works (provided
you managed to make goforestdb installation work)

Change-Id: Ief4a12048e08ab070a61568f133e7eb1d99055b8
Reviewed-on: http://review.couchbase.org/41759
Reviewed-by: John Liang <johliang00@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>