added 3 examples for google sheets API

these 3 minimalistic examples should demonstrate
how to use google sheets APIs. There are also
some explanations for each of the examples.

examples/gogol-examples.cabal

@@ -19,6 +19,7 @@ library
 
     exposed-modules:
           Example.Storage
+        , Example.Sheets
 
     build-depends:
           base          >= 4.7
@@ -28,6 +29,8 @@ library
         , gogol         == 0.3.0.*
         , gogol-core
         , gogol-storage
+        , gogol-sheets
         , lens
         , resourcet
         , text
+        , aeson

examples/src/Example/Sheets.hs

@@ -0,0 +1,54 @@
+{-# LANGUAGE OverloadedStrings #-}
+
+module Example.Sheets where
+
+---------------------------------------------------------------------------------
+import Network.Google.Resource.Sheets.Spreadsheets.Get
+import Network.Google.Sheets
+import Network.Google
+
+import Control.Lens           ((.~), (<&>))
+import Data.Text              (Text)
+import System.IO              (stdout)
+import Data.Aeson.Types
+
+---------------------------------------------------------------------------------
+
+-- | 
+-- This gets the Information about an spreadsheet.
+-- In order to be able to run these examples you need to
+-- create a service acount from google's developers console
+-- and copy the dowloaded json file to ~/.config/gcloud/application_default_credentials.json.
+--
+-- you must also share with your service the spreadsheet that you want to get the info of.
+-- In order to do this you must share the sheet with the email address of your service
+-- which is in your downloaded service config file.
+--
+-- after doing above step just pass the sreadsheet id to the function.
+exampleGetSheet :: Text -> IO Spreadsheet
+exampleGetSheet sheetID = do
+  lgr <- newLogger Debug stdout
+  env <- newEnv <&> (envLogger .~ lgr) . (envScopes .~ spreadsheetsScope)
+  runResourceT . runGoogle env $
+    send (spreadsheetsGet sheetID )
+
+-- |
+-- you pass the sheet id and a range (eg. "sheet1!A1:C3") in that sheet 
+-- and it retreives the values in the specified range
+exampleGetValue :: Text -> Text -> IO ValueRange 
+exampleGetValue sheetID range = do
+  lgr <- newLogger Debug stdout
+  env <- newEnv <&> (envLogger .~ lgr) . (envScopes .~ spreadsheetsScope)
+  runResourceT . runGoogle env $
+    send  (spreadsheetsValuesGet sheetID range )
+
+
+exampleAppendValue :: Text -> Text -> [[Value]] -> IO AppendValuesResponse
+exampleAppendValue sheetID range val =  do
+  lgr <- newLogger Debug stdout
+  env <- newEnv <&> (envLogger .~ lgr) . (envScopes .~ spreadsheetsScope)
+  runResourceT . runGoogle env $
+    send  (svaValueInputOption .~ Just "USER_ENTERED" $ spreadsheetsValuesAppend 
+          sheetID 
+          ( vrMajorDimension .~ Just VRMDRows $ vrValues .~ val $ vrRange .~ Just range $ valueRange) 
+          range )