Add support for an array of equalogic backends

* Modifies the AttributeParamStorage to support an array of items
* Adds some methods to pull the correct values out of the cinder model to
be passed to the puppet code.
* Add a calculation of the multiple_backends param
* Modify the params to store as json instead of individual fields
  The name now terminates at the index
* Move form to a partial, and render as necessary with javascript
* Validations now work and match up with correct fields
JS fixes and a remove button.
Merge pull request #289 from bcrochet/bz/1117464

Add support for an array of equalogic backends