Exit with nonzero status if t:start returns anything but 'ok'
Exit with nonzero status if t:start returns anything but 'ok'

Note that since all our tests don't currently pass this will make
builders turn red, but Steve says it shouldn't break Wallace.

Change-Id: I5b5936b521e6e0e8e4a029ff1db5f625e7e9beea
Reviewed-on: http://review.membase.org/3512
Reviewed-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>

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