Sysand git repositories as usage sources

@Simas this was very useful, thanks. It works for me from your repo, tested here: Usages from local filesystem indexes - #4 by sean . As in that link it did not work from my personal repo. I have not yet figured out why (error in the kpar build or error in the usage URL resolution).

This will be my solution going forward. Looking forward to native git support as a source.

@Simonas Thanks