Backward-compatible refactors.

Better handling of multiline Strings; more consistent use of
`$stdout.puts` instead of just `puts`; use `enum_for` instead of
defining a custom `Enumerator.
Add a spec for the CLI.
Ignore the coverage directory.
Re-record the VCRs to ensure the changes do not break anything.
Merge pull request #3 from swipely/minor-refactors-and-testing-improvements

Minor refactors and testing improvements