Fixed Chargeback Rate display

Fixed code to display of Cloud/Infrastructure providers rates after Save
Code fix properly identifies any EMS as such
Refactored code for better readability

Linked similar GitHub issue to the BZ ticket

https://bugzilla.redhat.com/show_bug.cgi?id=1073083
https://github.com/ManageIQ/manageiq/issues/138#event-148990147
@chessbyte I'd almost rather have the classes define their chargeback_show_typ method.  Either way, it seems complicated to have different rules for different classes like this.  I'm not sure why MiqEnterprise is "enterprise" and "EmsCluster" is ems_cluster, etc.  It would be nice to normalize these names to match a common pattern to make this less complicated but I have no clue of the context.