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 #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...

Revert "Fixes #13424 - Add Patternfly Donut Chart React component"

This reverts commit f4b2a11615d14ba1407aecd55523cd44d1010e14.

Fixes #13424 - Add Patternfly Donut Chart React component

Our donut charts do not look like they should in Patternfly.
https://www.patternfly.org/patterns/donut-chart/ uses c3, so we can do
that too.
Eventually I want to remove flot_pies too, but I have to yet figure out...

fixes #13144 - enable missing precompiled asset errors in test env

Remove extraneous ace/ace JS, which is included through vendor.

Fixes #11618 - Replace validation tests by shoulda-matchers

A good chunk of our unit tests are testing whether a validation is
working or not by testing it actively. For the validations we've
added ourselves I would say it's fine. However for validations that...

Fixes #13050 - Do not pass paths with /assets to helpers

Sprockets 3 does not recommend that, and the new option
`config.assets.raise_runtime_errors` on development.rb will raise errors
on development when doing it.

We only do it in one stylesheet and a helper, so fixing those let...

fixes #12914 - update configurations to rails 4.1 structure

this is a simple output after comparing the output of ```rails new foreman```
and updating accordingly.

fixes #12714 - Show proxy status in index, and create a show page for proxy

Fixes #7230, #12021 - Upgrade to Rails 4.1.5

This commits upgrades Rails to Rails 4.1.5. See a description of the
changes included here, and go to the pull request in GitHub to see more
detailed explanations:

• Update gems to a Rails 4 compatible version, including dependencies...