disable email alerts by default
disable email alerts by default

Because sending email to root@localhost (our default setting) makes no
sense at all. So lets make sure somebody configures it first.

Change-Id: Ib37d004135238e8c6e4f553a9bd149703f93e1fc
Reviewed-on: http://review.couchbase.org/13609
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>
Reviewed-by: Aliaksey Artamonau <3c875bcfb3adf2a65b2ae7686ca921e6c9433147@gmail.com>

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