[pdal] Docker for PDAL

[Howard Butler]

All,

In an effort to improve our Travis continuous integration times [1] (the automated tests that run every time we push new code to the PDAL repository), we have implemented PDAL Docker images. There are currently two images available -- the first is pdal/dependencies, and it is used to fetch/configure/build most of the stuff described in the compilation document [2]. The second is the PDAL image itself, which our Travis configuration doesn't actually use, but other people may find useful. 

You can find these images on hub.docker.com at https://hub.docker.com/r/pdal/dependencies/ and https://hub.docker.com/r/pdal/master/  I am working on a document much like the Vagrant tutorial that will show how you can use the Docker configuration to do things with PDAL. It should be available in the next day or two.

Thanks to Brad Chambers, Michael Gerlek, and Mike Smith for their Dockerfile work that bootstrapped this effort.

Howard

[1] https://travis-ci.org/PDAL/PDAL/builds
[2] http://www.pdal.io/compilation/unix.html