Fixes #5504: Consolidates Katello about page information to the Foreman about page.

Removes the Katello about page and uses deface to add two status widgets
to the Foreman about page. The two widgets are the backend status information
for services such as Pulp and Candlepin and a widget that lists installed packages.
Merge pull request #4018 from ehelms/fixes-5504

Fixes #5504: Consolidates Katello about page information to the Foreman ...