notifications: no email for app up/down/oom events

emails will not be used for self monitoring events. these are best done
from the outside. we just log everything in eventlog and raise notifications
as well.

src/notifications.js

@@ -166,8 +166,6 @@ function oomEvent(eventId, app, addon, containerId, event, callback) {
     }
 
     forEachAdmin({ skip: [] }, function (admin, done) {
-        mailer.oomEvent(admin.email, app, addon, containerId, event);
-
         add(admin.id, eventId, title, message, done);
     }, callback);
 }
@@ -178,7 +176,6 @@ function appUp(eventId, app, callback) {
     assert.strictEqual(typeof callback, 'function');
 
     forEachAdmin({ skip: [] }, function (admin, done) {
-        mailer.appUp(admin.email, app);
         add(admin.id, eventId, `App ${app.fqdn} is back online`, `The application installed at ${app.fqdn} is back online.`, done);
     }, callback);
 }
@@ -189,7 +186,6 @@ function appDied(eventId, app, callback) {
     assert.strictEqual(typeof callback, 'function');
 
     forEachAdmin({ skip: [] }, function (admin, callback) {
-        mailer.appDied(admin.email, app);
         add(admin.id, eventId, `App ${app.fqdn} is down`, `The application installed at ${app.fqdn} is not responding.`, callback);
     }, callback);
 }