Foreman Maintain

Update the satellite upgrade to new code

Extract control flow of upgrades to special file

Poor man's maintanence mode though ip tables

Move sync-plans checks to pre/post migrations

Introduce run_strategy for scenarios

Health-check scenarios are better to run all steps regardless of errors
(:fail_slow strategy), while the migration scenarios should fail as soon
as first failure happens (:fail_fast strategy).

By default, the scenarios are treated as `:fail_fast`.

Full upgrade scenario

This commit intoroduces more structured upgrade scenario consisting of
this scenarios:

• pre_upgrade_check - non-modifying checks: is the system ready?
• pre_migrations - modifying procedures before source update
• migrations - source update and main migrations...

Retain original objects while Tsorting. TSort create label graph and then convert to object graph

Define order using ruby TSort

1. Introduce 2 metadata: 'before' and 'after'
2. Current order is:
Checks::SyncPlans::WithEnabledStatus
Checks::DiskSpeedMinimal
Checks::SystemRegistration
Checks::ForemanTasks::NotPaused
Checks::ForemanTasks::NotRunning
Checks::ForemanTasks::Invalid::CheckOld...

Fixes #59 - missing error for hammer-config file

Assumeyes option