Bump stack to lts-6.12 and remove extra pkg from extra-deps
Bump stack to lts-6.12 and remove extra pkg from extra-deps

Signed-off-by: Michal Terepeta <369df49275e5bc251c4c73f6250cec386e4069c3@gmail.com>

snowleopard/hadrian,sdiehl/ghc,sdiehl/ghc,izgzhen/hadrian,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,snowleopard/shaking-up-ghc,bgamari/shaking-up-ghc,sdiehl/ghc,sdiehl/ghc