v0.4.0

• Dropped support for Ruby 1.8.7
• Refactored internals to avoid touching user's work tree - all
  conjuring is done in a temporary shared clone, fetched and merged
  from there
• Module metadata is stored in Git notes; new vendor info command
  shows it.
• Test dependency cleanup (use up-to-date Cucumber and Minitest)
• Support for external fetching tools with predefined shortcuts for
  Bundler and Berkshelf