Fix hard dependency of project.clj file of distill function.

No matter whether you pass the optional `:repositories` argument to `distill`,  `(project-repositories still)` will always be evaluated since it is in an `:or` binding map:

    [dependency & {:keys [repositories still verbose]
                 :or {still the-still
                      repositories (project-repositories still)
                      verbose true}}]

And this form throws FileNotFound exception if there is no project.clj file in current working directory.  

Propose this fix so `alembic` can be used in standalone lein repl.