#17 Add stream::getInfo() to return stream information

[Ramandeep Singh Bhatia]

Request to add stream::getInfo() to return information about the particular
stream.

We need a method to query different stream properties. Alternatively, this
functionality can be supplied as separate methods.

I imagine implementing this would be trivial since the stream class already
carries around all this information; it is a matter of putting together the API
to expose the values.

Device* device stream::getDevice()
stream::getRank()
stream::getDimensions()