use membase version if it's given
use membase version if it's given

Change-Id: Ie733164d2c3cf72db265e66851e01b547fae0e3a
Reviewed-on: http://review.membase.org/5446
Reviewed-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>

membase/ns_server,mschoch/ns_server,daverigby/ns_server,nimishzynga/ns_server,vzasade/ns_server,pavel-blagodov/ns_server,pavel-blagodov/ns_server,nimishzynga/ns_server,membase/ns_server,t3rm1n4l/ns_server,pavel-blagodov/ns_server,membase/ns_server,mschoch/ns_server,nimishzynga/ns_server,mschoch/ns_server,vzasade/ns_server,t3rm1n4l/ns_server,mschoch/ns_server,membase/ns_server,mschoch/ns_server,ceejatec/ns_server,daverigby/ns_server,nimishzynga/ns_server,t3rm1n4l/ns_server,t3rm1n4l/ns_server,vzasade/ns_server,membase/ns_server,membase/ns_server,daverigby/ns_server,daverigby/ns_server,nimishzynga/ns_server,t3rm1n4l/ns_server,ceejatec/ns_server,ceejatec/ns_server,daverigby/ns_server,mschoch/ns_server,vzasade/ns_server,ceejatec/ns_server,nimishzynga/ns_server,ceejatec/ns_server,ceejatec/ns_server,pavel-blagodov/ns_server