Let Timeline check EventStream class.
Let Timeline check EventStream class.

So Timeline can get both EmsEvent and MiqEvent for EVMAlertEvent.
https://bugzilla.redhat.com/show_bug.cgi?id=1306308
(transferred from ManageIQ/manageiq@50085ffdbdb9e282dc980d83040399bed6670ffe)

ManageIQ/manageiq-ui-classic,ManageIQ/manageiq-ui-classic,ManageIQ/manageiq-ui-classic,ManageIQ/manageiq-ui-classic