Updates requirements.txt with djoser version 0.2.1 and removes github reference.
Updates requirements.txt with djoser version 0.2.1 and removes github reference.

slashk/goldstone-server,slashk/goldstone-server,Solinea/goldstone-server,Solinea/goldstone-server,slashk/goldstone-server,Solinea/goldstone-server,slashk/goldstone-server,Solinea/goldstone-server,Solinea/goldstone-server,slashk/goldstone-server