fail rebalance if janitor run fails
fail rebalance if janitor run fails

While looking MB-5247 I've noticed that we're ignoring return value of
janitor cleanup run. Which should be fixed.

Change-Id: Ie32c2308ca75874037c289c0dfe925a317f59cb4
Reviewed-on: http://review.couchbase.org/15717
Reviewed-by: Aliaksey Artamonau <3c875bcfb3adf2a65b2ae7686ca921e6c9433147@gmail.com>
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>

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