Change environment test to check for 'physical'

Instead of checking against different types of virtual
hardware, we can test against 'physical', which should
mean we're not in Vagrant. If this doesn't work, we can
also set a custom fact in the Vagrantfile.
Add quickstart_env_is_staging()

Add an environment variable when Quickstart is provisioned
depending on the current environment. We can use that
in PHP to for our `quickstart_env_is_staging()` function.

Fixes #346
Change environment test to check for 'physical'

Instead of checking against different types of virtual
hardware, we can test against 'physical', which should
mean we're not in Vagrant. If this doesn't work, we can
also set a custom fact in the Vagrantfile.
Merge pull request #347 from Automattic/issue-346

Add `quickstart_env_is_staging()`
Remove phpinfo

Relevant info is in Query Monitor
Clean up wp-config
Revert "Merge branch 'feature/wp-debug-override' into develop"

This reverts commit 6c8e77669a5a6b2e62b79284617fd714d5bd4a15, reversing
changes made to e8e2aa51b5e68b258a4448a032335cf7cfa5f27b.
Merge branch 'master' of https://github.com/Automattic/vip-quickstart into develop

Conflicts:
	www/wp-config.php