Enhancement to Show External Authentication Configuration

- Added new entry in the appliance console summary screen
to show a new "External Auth:" entry indiciating either
"not configured" or the IPA Server hostname.
- Also showing current external authentication configuration
before giving the option to unconfigure.

Note: diff best viewed/understood while ignoring whitespace via https://github.com/ManageIQ/manageiq/pull/202/files?w=1

Instead of making a string and converting to regex, you can just do it directly...

```ruby
pattern = %r{[domain/.*].*(\n.*)+#{what} = (.*)}
config[pattern, 2]
```

Additionally,
- You may want to consider using named matches for better readability.
- `what` may have to be regex escaped depending on the content.