Switch to manylinux2010-compatible wheels

[lonvia]

PEP571 has been out for a while and we should switch to providing manylinux2010-compatible wheels. @wiktorn would you have time to look into this?

[wiktorn]

Sure, I'll take this one. Also will take into consideration osmcode/pyosmium#123

[lonvia]

Great, thanks. I tried to update pybind11 as this was suggested as a possible solution to osmcode/pyosmium#123 but the last build failed completely on something that looks completely unrelated. Hopefully that gets fixed with an updated manylinux as well..

[wiktorn]

The build failed because of API change in pip, see: matthew-brett/multibuild#298, this is fixed in devel branch of multibuild.

For now, the builds fail on the other issue (on macOS, only python2.7): matthew-brett/multibuild#305 for which I hope there is simple workaround.

Python3.4 is no longer supported on macOS so I dropped it in .travis.yml

Waiting for build results.

As far as I tested (python3.6) this fixes osmcode/pyosmium#123.