Expand testing and improve diagnostics

Merge pull request #214 from texadactyl/master

Improve testing and error messaging

Catching up to version 2.0.15

Update pythonpublish.yml

Changed 
types: [created]
to
types: [published]

JOSS release

Changelog:

• Added CONTRIBUTIONS.md
• Improved docstrings
• Fixed Travis-CI docker issues

Marking current version as 1.3.5. To be added to pipy

Former-commit-id: b6bea90b49cb0e6d1ef2195dfa171286515cc30b

1.3.4: Marking current version as 1.3.5. To be added to pipy

Former-commit-id: b6bea90b49cb0e6d1ef2195dfa171286515cc30b