Travis ci integration

[noeleont]

Problem
Currently we have a suboptimal review process, a proper travis ci integration would help us improve this process.

Goal

• Validate coding style (PEP 8)
• Automatic test

We could even think about a system to enforce new tests for new code, but I'm not sure if that's possible.

[noeleont]

I'd also like to see a way to check if all necessary translations were included in a commit.