JSCBC-709: Fixed testing of 5.5.6 due to user management tests.
JSCBC-709: Fixed testing of 5.5.6 due to user management tests.

Motivation
----------
User management was not available in older versions of
Couchbase Server.  This causes testing to fail on some
versions of Couchbase Server where it is not supported.

Changes
-------
Adjusted test feature control flag to only tests on
certatin Couchbase Server versions.

Change-Id: I26926a9913275bec9d0a6d85f3dc8b21f40c550e
Reviewed-on: http://review.couchbase.org/124053
Reviewed-by: Michael Reiche <150818245b00123390f022db0bae4daa40ee9511@couchbase.com>
Tested-by: Brett Lawson <c8c4369773d7d7226e031f0c4af62e3f38a08510@gmail.com>

couchbase/couchnode,brett19/couchnode,couchbase/couchnode,brett19/couchnode,couchbase/couchnode,couchbase/couchnode,brett19/couchnode