Please change version number tag to SemVer standard

[wshands]

We are using Python SemVer to to compare workflow/tool version strings in CGP, and SemVer doesn't approve of the CNV version number 'v1.0.5'. Would you please remove the 'v' prefix on the version number?
Example error message:
File "/usr/local/lib/python2.7/dist-packages/semver.py", line 51, in parse
raise ValueError('%s is not valid SemVer string' % version)
ValueError: v1.0.5 is not valid SemVer string

https://python-semanticversion.readthedocs.io/en/latest/index.html
http://semver.org/