fixes #14820 - override Rails log level with Foreman::Logging config

The log_level is expected to be explicitly configured in the Rails
config in the production environment.

Fixes #14778 - Ensure parsing complex types keep target type

Without this patch, the config task would send complex types as
strings to the setting model.

This patch makes the parsed object to keep the target type and it
assumes the setting model will do the internal conversion (now to...

fixes #14741 - translate template kind string, not object

Also convert translation keys to strings in debug mode to prevent
concatenation errors.

fixes #13244 - update Rails to 4.2.6

- Add responders gem to support class-level respond_to usage
- http://edgeguides.rubyonrails.org/4_2_release_notes.html#respond-with-class-level-respond-to
- Replace foreigner with native Rails 4.2 FK support
- uses a patch from Rails 5 to support Foreigner's...

fixes #14638 - Refactor Subnet into STI to allow different subnet types

Fixes #14645: fix production images for plugins.

Images were going through the legacy asset helpers in
sprockets-rails, this commit sets some options on the context
class to ensure we are looking up digested images in the correct
path.

http://projects.theforeman.org/issues/14645

Fixes #12318 - support preview for deb-based distros

Fixes #14508 - foreman-rake console can take arguments

One can now say e.g.

foreman-rake console -- --sandbox

We need the --, otherwise foreman-rake itself tries to interpret the flags

Fixes #14479 - removed unwanted check for token param

fixes #9782 - implement mediapath for suse/yast