Replace device.get_name with device.get_stream_id

The README and index.rst call a nonexistant get_name() method on a
Device object. The correct call is get_stream_id().
Rename get_connected() to is_connected()

The README and index.rst examples call a non-existant is_connected()
method on Device. Rather than blindly changing the docs to match the
code, the better solution in this case is to rename get_connected() to
is_connected() to match the boolean return type of the method.
Merge pull request #3 from nastevens/fix-tutorial-example

Fix tutorial example