Button Group: Fix 'Display on Button' checkbox visibility

[mzazrivec]

This is addressing problem described in #3383 (comment) and #3424 (comment)

1. Add / Edit of a Button Group should not produce error
2. Display on Button checkbox should be consistent in both the edit & details screen.

[true, "1"] because historically you'll find both in the database.

@himdel

[miq-bot]

Checked commit mzazrivec@55e7cd3 with ruby 2.3.3, rubocop 0.52.0, haml-lint 0.20.0, and yamllint 1.10.0
2 files checked, 1 offense detected

**

• 💣 💥 🔥 🚒 - Linter/Haml - Linter::Haml STDERR:

warning: parser/current is loading parser/ruby23, which recognizes
warning: 2.3.5-compliant syntax, but you are running 2.3.3.
warning: please see https://github.com/whitequark/parser#compatibility-with-ruby-mri.

[himdel]

LGTM, verified that this

• doesn't crash
• the checkbox is consistent across edits (_group_form) and when viewing (_ab_list)

👍

(kicking travis and waiting :))

[simaishi]

Gaprindashvili backport details:

$ git log -1
commit 1d340c0bb3091222dfb878be51dd81004686f1cb
Author: Martin Hradil <[email protected]>
Date:   Tue Feb 20 16:04:36 2018 +0000

    Merge pull request #3431 from mzazrivec/fix_display_on_button_checkbox
    
    Button Group: Fix 'Display on Button' checkbox visibility
    (cherry picked from commit d3819e4d9fae5f823a59972452ae26b5267aae17)
    
    https://bugzilla.redhat.com/show_bug.cgi?id=1553214