Fix pantheon site URL output in logs

[incredimike]

This PR is a simple fix to logging output.

Currently, the site environment hostname output to console is incorrect. See example below:

$ terminus pc ucf-sdes.dev
[notice] Multiple Pancakes Applications were found: Sequel Pro, SequelAce, MySQL. Add --app to be specific on the app.
[notice] Opening dev-ucf-sdes.pantheon.io database in Sequel Pro.
$

The host should be: dev-ucf-sdes.pantheon.io. It's missing the string "site" in the output.

I also noticed around line 50 in PancakesCommand.php the same string .pantheon.io is used when creating some IDs, but but those IDs probably don't need to change(?) so I left it.