WIP: DNM: Add support for an array of equalogic backends

Modifies the AttributeParamStorage to support an array of items
One thing to test here, with the move to multiple independent fields. If 'lvm' is selected (i.e. 'true'), then the user changes layout to one where it's not available (i.e. 'HA'), then comes back -- lvm is removed from the form, but it still may be selected in the object -- so there would be no way to clear this out. With the radio button scenario, it was solved by the fact that *something* had to be submitted, so that would override what was there before.