haskell-protocol-buffers: only mark as broken for GHC 7.8.3
Merge pull request #3606 from ederoyd46/haskell-protocol-buffers

haskell-protocol-buffers: only mark as broken for GHC 7.8.3
add pythonPackages.detox
update cran packages
manually fix dplyr and png cran-packages
r-RcppArmadillo: update to version 0.4.300.0
cran-packages.nix: added missing sha256 fields
cran-packages.nix: drop trailing whitespace