Cbc can be installed with conda

[tkralphs]

I just wanted to alert folks to the fact that there is an officially supported conda package for Cbc that can be installed on Linux and OSX with conda create -n cbc coin-or-cbc -c conda-forge. This will be kept up-to-date with the latest releases of Cbc. It could be useful for python-mip to check whether Cbc has been conda installed and to use that version automatically if it is present (although conda will only install releases and python-mip currently uses the master branch of Cbc).