support jsonb type (from postgresql 9.4)

Note, that this patch was not generated by the script in tools.
minor cleanup

 * import Data.Attoparsec.ByteString.Char8 instead of deprecated
   Data.Attoparsec.Char8 (the minimal supported attoparsec library version
   has it),
 * remove unused Applicative import,
 * remove trailing whitespace.
Merge pull request #118 from ibotty/jsonb-support

add jsonb type