More integration test coverage for dependency substitution

[bigdaz]

I think we need more coverage for replacing an external dependency with a project dependency:

• [x] Interaction with forced versions and other resolve rules
• [x] Replacement of transitive dependencies (could be added to existing test case)
• [x] Conflict resolution where 2 external dependency versions are in graph, but only one version is replaced by project dependency
• [x] Real resolution of dependency files: pre-build the substituted project. (This test would later be modified to remove the pre-build step).

[bigdaz]

More here: https://github.com/gradle/gradle/blob/master/design-docs/dependency-substitution.md#test-coverage

[lptr]

All of these should be done now.