fill user name when trying auth from cookie
fill user name when trying auth from cookie

First, this is most likely correct user name. And second, this will
present user with filled in user name when inactivity logout will
happen.

Change-Id: I0343bf5382a31af006f4f330f917f92589f6338f
Reviewed-on: http://review.membase.org/3680
Reviewed-by: Sean Lynch <9c3328a4a1f4f8f5c18b2d5b9057163c49b93ff3@literati.org>
Tested-by: Sean Lynch <9c3328a4a1f4f8f5c18b2d5b9057163c49b93ff3@literati.org>

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