Added a local docker provider that still uses the REST api, but doesn't have to publish all ports on a container.
Added the local Provider to the ProviderSupplier. docker.provider system property is now passed on to the ITs.
Updated README with information about different docker providers.
Updated README with more up-to-date example.
Merge pull request #7 from wouterd/feature/local-docker-provider

Feature/local docker provider