Centos package

[mottosso]

Goal

Provide binaries for Centos 6

Implementation

As I couldn't find any pre-compiled binaries, looks like we'll have to build it from scratch. Rather than build it for each new release, I'll build it once in a Docker image, and expose this to Travis.

Reference

• https://github.com/jemc/docker-qt5/blob/master/Dockerfile
• http://doc.qt.io/qt-5/linux.html
• http://www.linuxfromscratch.org/blfs/view/svn/x/qt5.html
• https://github.com/h2oai/h2o-2/wiki/Installing-python-2.7-on-centos-6.3.-Follow-this-sequence-exactly-for-centos-machine-only
• https://wiki.qt.io/Building_Qt_5_from_Git