Load the custom.css that bypasses the asset pipeline on every screen

[skateman]

Asset precompilation on appliances is no longer possible, however, in some cases it is necessary to have custom styling applied on a running appliance. This can only be done by bypassing the asset pipeline and loading a CSS file directly from the public folder. To avoid 404 errors an empty CSS file has been created in the core repo.

Depends on: ManageIQ/manageiq#17127
Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1553353

@miq-bot add_label pending core

[himdel]

@skateman I think also app/views/dashboard/saml_login.html.haml

Otherwise LGTM 👍 (waiting for core PR)

[miq-bot]

Checked commit skateman@65cd2e2 with ruby 2.3.3, rubocop 0.52.1, haml-lint 0.20.0, and yamllint 1.10.0
0 files checked, 0 offenses detected
Everything looks fine. ⭐

[simaishi]

Gaprindashvili backport details:

$ git log -1
commit 0cd3c3e1963345c62d2e119552a25c2117f3adf0
Author: Dan Clarizio <[email protected]>
Date:   Fri Mar 9 08:01:35 2018 -0800

    Merge pull request #3556 from skateman/custom-css
    
    Load the custom.css that bypasses the asset pipeline on every screen
    (cherry picked from commit 0e08eda9e9e1f6fccf7154d619d6e49752b1c134)
    
    Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1553841