Replacing `link` for almost all cases.
The `link` stanza can still appear in error messages, because
under the hood, `app` is still implemented as a pure synonym
for the `link` artifact. That will change automatically when
we factor into separate artifacts.
- add new file "cask/utils.rb" analogous to "utils.rb" in Homebrew
- define odebug and odumpcask, analogs of ohai and friends, but
which only give output when --debug is in effect
- move the debug setting from an instance variable in Cask::CLI
to a method Cask.debug, defined in "lib/cask/options.rb", which
was added in #2276. (Perhaps options.rb should be merged back
into Cask::CLI).
- sprinkle odebug statements liberally throughout the codebase
- update tests
the create command opens up an editor with template to get started
remove --create override flag from `brew cask edit`
hopefully this will be more straightforward for contributors
refs #306
