* Make photon client into a C extension.
* Fix formatting.
* Rename extension from PhotonClient to Photon.
* Update common submodule.
* Fix Makefile to compile with fPIC.
* Update common submodule.
* Compile C extension against common.
* Fix formatting.
* Remove unnecessary include.
* Update common submodule and rename Photon -> PhotonClient.
* Drop global interpretor lock during get_task.
Robert Nishihara