Changes to move out any AR Objects out of session/@edit hash

- Made changes to automate explorer code to move out AR Objects out of @edit hash and set the keys in @edit as array of hashes.
- Changed controller/views to use get/set them as hash values.
Calling #miq_group & #current_group should return the correct object type
Addressed rubocop comments
Merge pull request #207 from brandondunne/fix_provision_failures

Calling #miq_group & #current_group should return the correct object type
Merge pull request #213 from h-kataria/ae_move_ARObjects_out_of_session

Changes to move out any AR Objects out of session/@edit hash
Set default_value_for PxeServer#customization_directory

https://bugzilla.redhat.com/show_bug.cgi?id=1081006
Migrate any PXE server #customization_directory that is nil to ""

https://bugzilla.redhat.com/show_bug.cgi?id=1081006