Either return the active StreamingContext (i.e. currently started but not stopped),
or recreate a StreamingContext from checkpoint data or create a new StreamingContext
using the provided setupFunc function. If the checkpointPath is None or does not contain
valid checkpoint data, then setupFunc will be called to create a new context and setup
Checkpoint directory used in an earlier streaming program. Can be
None if the intention is to always create a new context when there
is no active context.
Function to create a new JavaStreamingContext and setup DStreams