Add test for Forcex.query

Since the stubbed out Api module does all the parsing of the JSON that's
returned the test doesn't exercise a ton, other than a url is called and
kind of documents the format of the returned data.

test/forcex_test.exs

@@ -1,7 +1,39 @@
 defmodule ForcexTest do
   use ExUnit.Case
 
-  test "the truth" do
-    assert 1 + 1 == 2
+  import Mox
+  setup :verify_on_exit!
+
+  test "query" do
+    response = %{
+      done: false,
+      nextRecordsUrl: "/services/data/v41.0/query/01g0W00006pQQsWQAW-2000",
+      records: [
+        %{Id: "0010W00002JBygyQAD", Name: "Michael Weber", attributes: %{type: "Account", url: "/services/data/v41.0/sobjects/Account/0010W00002JBygyQAD"}},
+        %{Id: "0010W00002JBw2mQAD", Name: "Erica Adams", attributes: %{type: "Account", url: "/services/data/v41.0/sobjects/Account/0010W00002JBw2mQAD"}},
+      ],
+      totalSize: 5989
+    }
+
+    endpoint = "https://forcex.my.salesforce.com"
+    api_version = "41.0"
+    auth_header = [{"Authorization", "Bearer sometoken"}]
+    query_path = "/services/data/v41.0/query"
+    query = "select Id, Name from Account order by CreatedDate desc"
+    query_url = "#{endpoint}#{query_path}/?#{%{"q" => query} |> URI.encode_query}"
+    IO.puts query_url
+
+
+    Forcex.Api.MockHttp
+    |> expect(:raw_request, fn(:get, ^query_url, _, ^auth_header, _) -> response end)
+
+      client = %Forcex.Client{
+        endpoint: endpoint,
+        authorization_header: auth_header,
+        api_version: api_version,
+        services: %{query: query_path}
+      }
+
+      assert Forcex.query(query, client) == response
   end
 end