Added ghcid-0.2

The .nix file was generated by cabal2nix. However, I still had to set
doCheck = false since some of the tests try to run `cabal repl` which
presupposes access to $HOME/.cabal and thus cannot be done from the Nix
sandbox where HOME = /homeless-shelter.
Merge pull request #4705 from jirkamarsik/ghcid

Added ghcid-0.2