Log the request in debug mode (#125)

* Log the request in debug mode

* Fixing typo in request logging

lib/oauth2/request.ex

@@ -1,6 +1,7 @@
 defmodule OAuth2.Request do
   @moduledoc false
-
+
+  require Logger
   import OAuth2.Util
 
   alias OAuth2.{Client, Error, Response, Serializer}
@@ -20,6 +21,17 @@ defmodule OAuth2.Request do
     headers = process_request_headers(headers, content_type)
     req_opts = Keyword.merge(client.request_opts, opts)
 
+    if Application.get_env(:oauth2, :debug) do
+      Logger.debug("""
+        OAuth2 Provider Request 
+        url: #{inspect url}
+        method: #{inspect method}
+        headers: #{inspect headers}
+        body: #{inspect body}
+        req_opts: #{inspect req_opts}
+      """)
+    end
+
     case :hackney.request(method, url, headers, body, req_opts) do
       {:ok, ref} when is_reference(ref) ->
         {:ok, ref}