Package project and set up platform testing with tox

[danijar]

• mindpark should be an optimized (-O) system executable after installation.
• How can people register their algorithms? Maybe define path in definition file like algorithm: {type: ./project_folder/file_name:ClassName}?
• Set up tox testing for Python 3.4 and 3.5.
• Set up continuous integration with Travis.
• Update dependencies (and add doom_gym) which is not part of gym anymore.