Adds back import to make GHC 7.8 happy

src/PostgREST/Auth.hs

@@ -17,6 +17,9 @@ module PostgREST.Auth (
   , tokenJWT
   ) where
 
+--line needed for ghc 7.8
+import           Data.Functor            ((<$>))
+ 
 import           Data.Aeson              (Value (..), Object)
 import           Data.Aeson.Types        (emptyObject, emptyArray)
 import           Data.Vector             as V (null, head)