Made changes to instance add/edit code to remove AR Objects from @edit

- Changed code to add/edit Instance to not store AR Objects in @edit instead store required fields into array of hashes. Made some minor cleanup along the way to methods edited in this commit.
- Changed view to use hashes to access data instead of AR Object.

https://bugzilla.redhat.com/show_bug.cgi?id=1114747
https://bugzilla.redhat.com/show_bug.cgi?id=1115652
Made suggested changes from PR review.

Removed code duplication from initial_setup_for_instances_form_vars method.

https://bugzilla.redhat.com/show_bug.cgi?id=1114747
https://bugzilla.redhat.com/show_bug.cgi?id=1115652
Remove @record from session and move grid xml from @edit to @temp

https://bugzilla.redhat.com/show_bug.cgi?id=1114747
https://bugzilla.redhat.com/show_bug.cgi?id=1115652
Changed to only save/update instance field if it's not nil.

Added a missing header column "On Error" in Instance grid, that was causing grid to display incorrect data in rows.

https://bugzilla.redhat.com/show_bug.cgi?id=1114747
https://bugzilla.redhat.com/show_bug.cgi?id=1115652
Merge pull request #139 from h-kataria/removed_ar_objects_from_ae_instance_editor

Made changes to instance add/edit code to remove AR Objects from @edit