Add support for manylinux2014

[mayeut]

Add support for manylinux2014

c.f. pypa/manylinux#338

manylinux2014 now also allows for different architecture than x86_64/i686
Images are also available for aarch64/ppc64le/s390x

[YannickJadoul]

Images are also available for aarch64/ppc64le/s390x

Seems Travis CI is/has been working on this: https://docs.travis-ci.com/user/multi-cpu-architectures/

[joerick]

Implemented in #215, Released in v1.1.0