Guardfile: Add guard-kitchen plug-in.

The guard-kitchen plug-in from Opscode uses test-kitchen to converge and
verify your cookbook as you modify it.  It does this by starting the
vagrant boxes when guard initializes (via `kitchen start`) and
converging or verifying as your recipe changes.
Rakefile: Fix unit-test task.

The unit-test task really should clean up after itself by removing the
vendored cookbooks.  This commit makes it so.
Vagrantfile: Use single quotes consistently.
FEATURES.org: Add feature tracking via Orgmode file.
Guardfile: Add ignore for dot files.