Issue #965: Update package.json github dependency to use git+https protocol

This was a pain to find out. Behind a firewall, git cannot be used. The
only way to use the dependency is through the git+https protocol.

https://github.com/atom/atom/issues/3703
https://github.com/atom/scoped-property-store/commit/f80af58fde1d9ae1d137b28dec4b0b0961eaae23

I'm using the current HEAD commit SHA in this commit and it worked.