Better handle requirements and edgecases with TAP

- Use SKIP instead of not ok for requirements.
- Look for ZFS in testcases where it's required.
- Use id -u instead of whoami for figuring out whether or not someone is
  root.
- Make an attempt at trying to clean up the memory disks and files in
  some of the testcases if the test scripts exit prematurely.

Sponsored-by: EMC / Isilon Storage Division
Integrate tools/regression/acltools into the build/kyua

Sponsored-by: EMC / Isilon Storage Division
Merge branch 'isilon-atf' into isilon-atf-acltools

Conflicts:
	etc/mtree/BSD.tests2.dist
	tests/sys/Makefile
Require root via kyua

This is done to avoid having to backport the SKIP/TODO TAP support
for devel/kyua-testers

Submitted-by: ecramer @ isilon
Sponsored-by: EMC / Isilon Storage Division
Merge pull request #8 from yaneurabeya/isilon-atf-acltools

Integrate tools/regression/acltools into the build/kyua