Release v1.6.0 (#324)

* Update version and changelog for v1.6.0
* Update docs
diff --git a/docs/epy/googleapiclient.errors-module.html b/docs/epy/googleapiclient.errors-module.html
index b8acabd..beaf83e 100644
--- a/docs/epy/googleapiclient.errors-module.html
+++ b/docs/epy/googleapiclient.errors-module.html
@@ -224,7 +224,7 @@
 <table border="0" cellpadding="0" cellspacing="0" width="100%%">
   <tr>
     <td align="left" class="footer">
-    Generated by Epydoc 3.0.1 on Tue Nov  1 17:02:49 2016
+    Generated by Epydoc 3.0.1 on Thu Jan  5 12:55:02 2017
     </td>
     <td align="right" class="footer">
       <a target="mainFrame" href="http://epydoc.sourceforge.net"