Code Review: testfixes-1

tfpt review /shelveset:testfixes-1;REDMOND\jflam

This fixes a broken test in run0 (test_dir.rb) which had a dependency on
the existence of environment variables that may not exist on local
developer machines.

It fixes the performance degredation in spec_runner.rb

It also fixes a number of specs that broke when we changed how
directories were traversed by spec_runner.

Thanks,
-John