Testplanet does not have a multinode instance, hence,
makes it difficult to run ui tests for the multinode dashboard.
Instead of using storj-sim for multinode ui tests,
it's better to use the same approach (testplanet) fir all UI tests.
This changes adds a multinode instance to testplanet.
Change-Id: I58aa8c4597e789275f9e7ea7059703c742903492