don't register/unregister ns_memcached too late/soon
don't register/unregister ns_memcached too late/soon

There's seeminly no need anymore. And it allows us to check if bucket
is still running by looking at registered processes.

Change-Id: Iecef1bed6690e20cc14d3f8caed2dbdcd27bf6ab
Reviewed-on: http://review.couchbase.org/14179
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>

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