Merge pull request #48 from weizenspreu/master

Make KeyboardReportParser::handleLockingKeys() virtual to override keyboard LED handling.
Added pair function
The SPP Class now inherit from the Arduino Stream library
Call send if the buffer would be full
Fixed some comments
Updated comment
added gearfreak's NAK limit fix
Check if Bluetooth address is set before writing to PS3 controller
Added more contributors
Merge branch 'master' of https://github.com/felis/USB_Host_Shield_2.0
Use __ instead of <b> in readme
Shift one so it the same as setLedOn etc.
Added KeyboardReportParser::OnControlKeysChanged(before, after) to be able to react on control key presses and enhanced the HID keyboard example.