Fix ListSwarmNodesCmdImpl and Add basic tests (#1385)

* Fix ListSwarmNodesCmdImpl and Add basic tests

- fixes withMembershipsFilter
- fixes withRoleFilter
- adds basic tests for the class.

* Update docker-java/src/test/java/com/github/dockerjava/cmd/swarm/ListSwarmNodesCmdExecIT.java

* Update ListSwarmNodesCmdExecIT.java

* use `startSwarm()`

Co-authored-by: Sergei Egorov <segorov@pivotal.io>
Co-authored-by: Sergei Egorov <bsideup@gmail.com>