doc: Remove dead files

The Sphinx themes now include Google Analytics code, therefore, it's not
necessary to keep the local version. In addition, some images are no
longer referenced anywhere and can therefore go away.

Change-Id: I4a3b48f726220e8db3dc79f0b4b5405df6d28f13
TrivialFix

doc/source/_ga/layout.html

@@ -1,17 +0,0 @@
-{% extends "!layout.html" %}
-
-{% block footer %}
-{{ super() }}
-<script type="text/javascript">
-var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www.");
-document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E"));
-</script>
-<script type="text/javascript">
-try {
-//Tracking docs.openstack.org/developer/nova only
-var pageTracker = _gat._getTracker("UA-17511903-1");
-pageTracker._setCookiePath("/developer/nova");
-pageTracker._trackPageview();
-} catch(err) {}</script>
-{% endblock %}
-