Release v0.2.0

Full Changelog

• 039b152 Make it so Options#default_branch does not actually run git (#17)
• 754224c Require date (#15)
• 7789a28 Do not hardcode the version file path (#14)
• 73b61bd Do not use unneeded regexps in tests (#13)
• 6fa12e5 Create the release tag before trying to create the release branch (#12)
• 819afd3 Call the right method for creating the release (#11)
• 8a0fe61 Fix error in the create-github-release script (#10)
• 6999d91 Execute the tasks from the create-github-release script (#9)
• 819b657 Add a changelog file (#8)
• 697fb95 Add 'tmp' and 'sig' directories to rake cleanup (#7)
• 993e121 Add release tasks (#6)
• a2d0b4d Add assertion to check that the git command is in the path (#5)
• c3ed55b Refactor assertions (#4)
• 0f3733e Add release assertions (#3)
• a2c00ee Add the CommandLineParser class (#2)
• 9535c0e Add the Options class (#1)