Add an error message if najax is not defined (that is it is overriden)
Add an error message if najax is not defined (that is it is overriden)

kratiahuja/ember-cli-fastboot,josemarluedke/ember-cli-fastboot,ember-fastboot/ember-cli-fastboot,josemarluedke/ember-cli-fastboot,ember-fastboot/ember-cli-fastboot,tildeio/ember-cli-fastboot,kratiahuja/ember-cli-fastboot,tildeio/ember-cli-fastboot