Refactor reset command to have subcommands.

* Move reset logic to data subcommand.
Add reset schema command.
Add album cover parody
Merge pull request #4 from midas/album-cover

Add "No Jacket Required" album cover parody to readme
Remove superfluous 'attr_reader' statement
Make 'envs' and 'tags' statements callable more than once
Introduce singular forms of 'envs' and 'tags' statements
Merge pull request #5 from midas/enhance-envs-and-tags

Enhance 'envs' and 'tags' DSL