v1.0.0

• Only the necessary packages are getting cloned, not resolving the whole dependency tree. For example if no package depends on elm-lang/core - 1.0.0 it and it's dependencies won't be resolved.
• Allow defining dependency source to a fork #16, or a completely unrelated repository which has a valid elm-package.json file.
• Allow defining dependency source to a local directory which has a valid elm-package.json file.