• Renamed rbenv set-default to rbenv global and rbenv set-local
  to rbenv local. The set- commands are deprecated and will be
  removed in the next major release.
• rbenv now uses greadlink on Solaris.
• Added a ruby-local-exec command which can be used in shebangs in
  place of #!/usr/bin/env ruby to properly set the project-specific
  Ruby version regardless of current working directory.
• Fixed an issue with rbenv rehash when no binaries are present.
• Added support for rbenv-sh-* commands, which run inside the
  current shell instead of in a child process.
• Added an rbenv shell command for conveniently setting the
  $RBENV_VERSION environment variable.
• Added support for storing rbenv versions and shims in directories
  other than ~/.rbenv with the $RBENV_ROOT environment variable.
• Added support for debugging rbenv via set -x when the
  $RBENV_DEBUG environment variable is set.
• Refactored the autocompletion system so that completions are now
  built-in to each command and shared between bash and Zsh.
• Added support for plugin bundles in ~/.rbenv/plugins as documented
  in #102.
• Added /usr/local/etc/rbenv.d to the list of directories searched
  for rbenv hooks.
• Added support for an $RBENV_DIR environment variable which
  defaults to the current working directory for specifying where rbenv
  searches for local version files.