improve ssh-access specs for owner/editor cases.
fix owner/editor related public/private_r problem.
make inclusion-questions nil-resilient.
mitigate some rspec deprecation warnings.
raise error on push to mirror repository.
handle push-to-mirror error in controller

Also add a new flag 'provide_to_user' which
determine whether the reason message could be
provided to the user via STDOUT.
refactor ssh-access related stuff by style-guide

Also make it possible to create an instance of SSHAccess instead of
using the 'whole-bunch-of-class-methods' approach.
expect to raise an explicit error.

Expect to raise SSHAccess::InvalidAccessOnMirrorError instead
of any error.
Merge pull request #955 from ontohub/952-allow_push_by_owner_permission

952 allow push by owner permission