ioHub docs update
ENH: launchHubServer device config file support

The launchHubServer function now (optionally) supports providing the
device config file path to use for loading device configuration details.
ENH: iohub getEvents(event_type=xxx) support

To specify the event type desired when calling getEvents(), the kwarg
'event_type' can now be used, which is == to the existing
'event_type_id' kwarg.
BF: Misc small eye tracker device cleanup.

-fixed some eye tracker device comments.
-Documented new default eye tracker config settings for Tobii
ENH: Added ioHub Touch device

- Currently support for Elo Touch Screens using the serial interface.
- Serial -> USB converter cable can be used.
- Allows independent monitoring of touch screen events from that of the
Mouse device; so both devices can be used in parallel and generate
different event streams.