Added distributed-process 0.5.

Bump binary dependency of rank1dynamic, distributed-static, network-transport-* to binary-0.7.2.1.
It might be possible to move those overrides to the file `haskell-default.nix`, which contains compiler-dependent configuration. As far as I can tell, the `binary` override is necessary only for GHC <= 7.6.3. GHC 7.8.x, on the other hand, ships with binary 0.7.x, so it's not necessary to replace the version of the library that comes with the compiler.