Batcave

- Added
- Added Docker Python API.

- Changed
- Fixed servermgr module use of sysutil.syscmd.

- Changed
- Improved menu.SimpleMenu implementation.
- Update setuptools to 38.5.1
- Update unittest-xml-reporting to 2.1.1
- Update p4python to 2017.2.1615960

- Changed
- Fixed issue using both lists and tuples.

- Added
- Added extra_vars argument to build.ConfigurationBuilder.

- Changed
- Update pypiwin32 to 222.
- Update PyQt5 to 5.10.
- Changed the repo reference file name.
- Always publish repo references in artifacts directory for Docker builds.

- Removed
- Removed slacker dependency.
- Removed obsolete static variable.

- Added
- Added support for Docker images push to Google Cloud registry.