Perform pylint on the repository and update dependencies of mayavi in Readme.md

[liubenyuan]

Hi, I saw that you are developing a branch with C++ support and refactoring the folder structure, I think

1. add pylint check (or enable travis or coverage.)
2. the 3D demo depend on mayavi, which currently is not supported in Anaconda with python-3.5 (which will be support in the next release of mayavi), I think this dependency should be written in the Readme.md