Make sure proposal validations do not break install

This references PR #894 and BNC #860117
Do not run validations from within the apply_role
Skip after_save validation on creating proposals

And add comment explaining why
Do not repeatedly look up the node in transition exit

Instead of looking up the node after each transition finishes,
load it once in the controller.
Merge pull request #945 from bkutil/feature/skip_node_load_on_transition_leave

Do not repeatedly look up the node in transition exit
Ensure backwards compatibility in transition

If a barclamp returns [status, node.to_hash], pass it along.
Merge pull request #946 from bkutil/fix/proposal_validations

Fix/proposal validations
Merge pull request #947 from bkutil/fix/backward_compatibility_in_transition

Ensure backwards compatibility in transition
Fix tests for proposal validations
Fix i18n parameter key in SupportController error
Add regression test for i18n key fix
Merge pull request #951 from bkutil/fix/i18n_param_fix

Fix/i18n param fix
Use Process.fork so we can stub it
Add back export implementation

Add back export of the stored data, called by SupportController and
accidentally removed in ff7e15ae365a685d2f19a828d744524b7518db0c.
Add test for SupportController#export_chef
Merge pull request #948 from bkutil/fix/test_fix_for_proposal_validations

Fix tests for proposal validations
Merge pull request #952 from bkutil/fix/add_back_chef_export

Fix/add back chef export
Use correct font size for list of nodes for roles

(cherry picked from commit 840f9258d5c46ae372a6c06518d6e16fa98a5b34)
Merge pull request #955 from vuntz/fix-font-size-stoney

Use correct font size for list of nodes for roles