(fix) Changed the versioning of phenotypes to semantic versioning using the last tag in the repo rather than the commit count. The user can specify if they want to increment major, minor or patch when they publish which keeps the versioning simple. Previosuly we used the commit count but that was problematic due to always incrementing the patch versions and if using an existing the commit history could be large. This would especiually be the case when forking a repo where the commit history is retained. Closes #51