add extensions to README.md.
Category initializer. version bumps.
deprecate preAction.
add tuning program.
update apiary-authenticate version restriction, update .travis-install.sh.
change Extension interface.
Revert "add tuning program."

This reverts commit 0e4b676821d155bb463e1cb10900b5744f225626.
update .travis-install.sh
update runner api.
update submodules.
update examples.
fix test.
compat. ghc-7.6.
fix examples.
fix dependency on ghc-7.6.
changge run api.
add apiary-mongodb.
update export list.
change case apiary-mongo'DB'.
add memcached.