- new struct: createNodeOpts for wait and timeout values
- new commands for creating/adding multiple nodes which then wait for
all nodes to be up, if specified
- tests/e2e: new test for adding a master node
- fixes startCluster's --wait/--timeout functionality
--> now doesn't check all the logs (e.g. from previous run)
----> no more false positives when checking for a specifc log message
only in the current run
- imageVolume couldn't be determined before in some cases, because it
tried to extract the name from labels on the masterlb which doesn't have
them.
- now we're only trying get the label from master/worker nodes and this
also adds a failover solution
- also, we ignore non-worker/master nodes upon image import
