Update .travis.yml
Update .travis.yml

adding notifications to our slack

Gaurav0/ember-table,hedgeserv/ember-table,phoebusliang/ember-table,Cuiyansong/ember-table,phoebusliang/ember-table,nomadop/ember-table,Gaurav0/ember-table,hedgeserv/ember-table,Cuiyansong/ember-table,nomadop/ember-table