Rollback to aeson 0.8.0.2 to allow building with stackage, and adds stack.yml

test/Feature/InsertSpec.hs

@@ -89,7 +89,7 @@ spec = afterAll_ resetDb $ around withApp $ do
       it "fails with 400 and error" $
         post "/simple_pk" "}{ x = 2"
           `shouldRespondWith` ResponseMatcher {
-            matchBody    = Just [json| {"message":"Failed to parse JSON payload. Failed reading: not a valid json value"} |]
+            matchBody    = Just [json| {"message":"Failed to parse JSON payload. Failed reading: satisfy"} |]
           , matchStatus  = 400
           , matchHeaders = []
           }