Importing ssbio on python2.7 cobra environment

[nmih]

Freshly installed cobra environment + ssbio runs into an import error for the package "ruamel_yaml", solved by:

pip install ruamel_yaml==0.11.14

See: https://stackoverflow.com/questions/41373834/conda-importerror-no-module-named-ruamel-yaml-comments

[nmih]

move to troubleshooting wiki