• Part of #125: Color borgmatic (but not Borg) output when using an interactive terminal.
• #166: Run tests for all installed versions of Python.
• #168: Update README with continuous integration badge.
• #169: Automatically sort Python imports in code.
• Document installing borgmatic with pip install --user instead of a system Python install.
• Get more reproducible builds by pinning the versions of pip and tox used to run tests.
• Factor out build/test configuration from tox.ini file.