Libby2019a

Add 'Cell culture/Human iPSC wt growth' for Libby2019 wildtype model to repo of published models. Model graph is included as svg but not embedded actively by index.md (could be added if needed). Two xml files are included, the originally published but now outdated and the new xml running in the current Morpheus. Just to avoid displaying both xml files in the automatically generated model section, I renamed the file extension to xml_original. This may not be necessary but this way the parser script knows which is the main xml.