Update mock version and add session level version method

The exporter model now uses the session level method to get the serrano version instead of relying on the version number in the exporter response. This removes duplicate parsing code and makes the serrano version available at the highest level to all models.
Add more robust check for Serrano version string
Add a method for checking if Serrano is outdated
Display a warning to the user if the Serrano version is outdated
Remove debug output
Remove unneeded step declaration
Merge pull request #207 from cbmi/issue-196

Add minimum Serrano version setting and warn user if it is not met