Release v1.6.0 (#324)

* Update version and changelog for v1.6.0
* Update docs
diff --git a/docs/epy/module-tree.html b/docs/epy/module-tree.html
index bdb9f44..fbaa6d1 100644
--- a/docs/epy/module-tree.html
+++ b/docs/epy/module-tree.html
@@ -57,6 +57,7 @@
 <ul class="nomargin-top">
     <li> <strong class="uidlink"><a href="googleapiclient-module.html">googleapiclient</a></strong>
     <ul>
+    <li class="private"> <strong class="uidlink"><a href="googleapiclient._auth-module.html">googleapiclient._auth</a></strong>: <em class="summary">Helpers for authentication using oauth2client or google-auth.</em>    </li>
     <li> <strong class="uidlink"><a href="googleapiclient.channel-module.html">googleapiclient.channel</a></strong>: <em class="summary">Channel notifications support.</em>    </li>
     <li> <strong class="uidlink"><a href="googleapiclient.discovery-module.html">googleapiclient.discovery</a></strong>: <em class="summary">Client for discovery based APIs.</em>    </li>
     <li> <strong class="uidlink"><a href="googleapiclient.discovery_cache-module.html">googleapiclient.discovery_cache</a></strong>: <em class="summary">Caching utility for the discovery document.</em>
@@ -101,7 +102,7 @@
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   <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
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       <a target="mainFrame" href="http://epydoc.sourceforge.net"