Split the GetSemanticVersion inline task into two parts, first the getting the version via GitHubFlowVersion.exe and second the parsing of the version JSON file. This allows the build to only get the version once and then reuse the version file each time the version number is needed.

references #11
Merge pull request #11 from pvandervelde/issue/getsemanticversiononce

Deploy script should re-use existing version number file