Review KateStatusBar

Summary:

• Move the modified label from far right to far left This way have it a more prominent position
• Don't gray out modified label
• Don't use labels as buttons
• Change to new signal/slot style
• Avoid Q_FOREACH
• Avoid unneeded stuff

Reviewers: KTextEditor, cullmann

Reviewed By: KTextEditor, cullmann

Subscribers: zetazeta, cullmann, kwrite-devel, kde-frameworks-devel, KTextEditor

Tags: Kate, Frameworks

Differential Revision: https://phabricator.kde.org/D17730