v0.5rc1

• Add a new pull checkout command to easily checkout a pull request. This
  is just a wrapper to the standard checkout command, but fetches and
  automatically adds the head reference of the selected pull request (#29)
• Add a --pause option to pull rebase command. This makes a pause just
  before pushing the rebased result back to the repository and updating the
  issue. This is similar to pull checkout very useful for testing the
  exact result of the rebase (#39, #44, 0fe1615)
• Allow creating pull requests from a headless checkout as long as
  --create-branch is specified (#33)
• Plus some minor bug fixes and improvements:
  • Fix some unicode-related problems when unicode is present in commit
    messages. Bare in mind branch names with unicode characters are still
    problematic, see #46 for details (#45)
  • Improve warning message in pull rebase when not the pull request is not
    in a mergeable state (495f87e)
  • Fix a problem with interrupted pull rebase while --edit-msg is used
    (#38)
  • Add missing documentation for pull rebase --force (#40)
  • Don't requite hub.upstream configuration variable to be set for
    clone, but require authentication (#36, #32)