Relax numpy version requirements about opencv-python

[skvark]

There are no numpy 1.11.1 builds for Python 3.6. If you are using older Python version than 3.6 it is possible to relax the version requirement.

A proper fix for the numpy requirement is to parameterize the numpy version for each build separately in the matrices to lowest possible version to maintain ABI compatibility. For Travis it should be implemented like this: https://github.com/MacPython/astropy-wheels/blob/master/.travis.yml and for Appveyor in similar way. This means also that the numpy requirement has to be removed from requirements.txt.

[adrianmoisey]

I did a test here: #30
And saw that it breaks on Windows.

If I made a patch, like what you describe above, would you merge it?

[skvark]

Yes, I would merge it. I'm finishing currently contrib modules support in another branch so if it's done within a week or so the fix be available in the next release.

[adrianmoisey]

I'll give it a try, thanks