name of the docker build for compilation should include platform and version

[kramasamy]

This will allow for the caching of the container when multiple environments are being built.

[ajorgensen]

The intermediate layers are actually cached so subsequent builds should not be replaced but use the cached layers from the previous run. So building with ubuntu and then centos and then ubuntu again you should not have to pay the building penalty on the second ubuntu run.

I'm going to add a tag to the docker container for each platform to help separate the images however I think its good change anyway.