Add possibility to supply io step with InputStream instead of a file path

Currently it is possible to supply io step with file path to read a file from file system.

It would be very convenient if we would be able to read files from input stream instead of file path. 

For example, it could look something like:

g.io(graphSonInputStream).with(IO.reader, IO.graphson).read().iterate()

Of course it wouldn't work as expected if we would use write instead of read here because we won't be able to write to the input stream. Thus, we can fail fast if the user supplied an input stream into the io step but tried to use write.