Nl replaced sync library

Replaced the sync-q library with my own synchronous queue library named - sink_q
Race conditions are fixed so users can call take picture without manually interleaving callbacks

Reviewed By: @johnnyman727
We have a SPI queue in the Tessel driver that should prevent that from happening. If a SPI request is already underway, the second call to `takePicture` would be queued up until the first completes.