add rake task for generating docs with YARD
to see this on command line with default :auto level we need to warn
CHEF-4307: Verify that chefignore is a file before reading it.
Ignore exit status 12 when deleting test user account

Various versions of `useradd` return a variety of errors with exit code
12 when removing a user with no home directory and given options
indicating the home directory should be removed, regardless of the `-f`
flag. This is fixed in newer versions (such as the version on Ubuntu
13.04, where these tests were originally written), but probably won't be
fixed for older OSes. Accepting exit code 12 should fix the tests on
these platforms.
Ensure usermod -d option comes before -m.

- Fixes CHEF-4305 http://tickets.opscode.com/browse/CHEF-4305
- Fixes RHEL/CentOS 5 usermod bug uncovered by functional tests.
Skip test for username with quote where unsupported.

Only debian-based platforms appear to support usernames with single
quote characters, so skip this test on other platforms.
Be more specific: check file? || symlink? instead of just directory?
Merge pull request #846 from opscode/fix-old-userdel-whining

Fix `usermod` test issues
Merge pull request #843 from opscode/lcg/warn-run-lock

to see this on command line with default :auto level we need to warn
Merge pull request #839 from opscode/lcg/yard

add rake task for generating docs with YARD