Exclude knife integration tests on server platforms

Not all platforms (looking at you solaris) need bother running the knife tests
because we don't consider them to be workstation platforms. Excluding them
will reduce transient failures and speed up the tests.
Revert "Merge pull request #2024 from opscode/jdmundrawala/windows_env_path"

This reverts commit 0d32643ea573e28c5e62e77b04fdbb5ee98d2a05, reversing
changes made to 40149734f91a2ff53409c02c69b43c10bc4e984d.