Merge pull request grid-parity-exchange#268 from grid-parity-exchange…

…/release_052

Egret release 0.5.2

Merge pull request grid-parity-exchange#257 from bknueven/setup_51

setting up 0.5.1; removing long description

Merge pull request grid-parity-exchange#256 from bknueven/setup_05

Setting up 0.5.0