Verify our results belong to the desired class.

(Change originally from commit
genome/genome@6e69c59c1ea3be7954f23bf59821c9c2ce2a9cff.)
Handle missing statuses.

(Change originally from commit
genome/genome@aa1c2c5def20d25b1a9dc10eac3de03c5bb8273e.)
Replace _unique_elements with List::MoreUtils::uniq.
Always read from the terminal when getting user input.

(Change originally from commit
genome/genome@ef611e88a199431918deaf70a206a797e88da5c5.)
Merge pull request #44 from tmooney/propagate_gcb_changes

Pull up changes from Genome::Command::Base