Added Python 3.7 compatibility

Fixed CI & added Python 3.7

* Fixed Travis CI build

* Updated zstd test binary blob

* Added: Python 3.7

* Fixed: change type of "information" for RAR

* Added: test the guesser alone to get better error message

* Increase major and update dependency

Latest and stable with additional fix for Python 2.7, 3.4, 3.5, 3.6

• Fixes the destructor not being called for ExternalPipe decompressors
• Clean-up print statements in the code on the release on pypi

Latest and stable with additional fix for Python 2.7, 3.4, 3.5, 3.6

• Fixes the destructor not being called for ExternalPipe decompressors

Stable release Python 2 & Python 3 compatible

Fix issue with python-magic and Python 3