NEW: Rewrite self.version in create-project (Fixes #1351)

When composer create-project is called and the resulting project is disconnected from the
parent repo, self.version references no longer work.  To fix that, this patch rewrites
self.version to the actual version number as part of 'composer create-project' execution.

As it stands, this code works, but I'm not sure how to best go about creating a test for it.  Any advice would be appreciated.