Allow logs(-dev).o.o to serve gzipped svg files

In https://review.openstack.org/#/c/396428/ we improved logs.o.o
to be able to serve statically generated html content/web applications
that have been gzipped.
The svg format was missed in that patch so that we can fully compress
output before uploading/storing it to logs.o.o.

We are first testing it on logs-dev.o.o and we will later apply it
to logs.o.o if it works well.

Change-Id: I0354f61f24176874a6590d32cfa06bb9cf3a02e3

templates/logs-dev.vhost.erb

@@ -16,7 +16,7 @@ NameVirtualHost <%= @vhost_name %>:<%= @port %>
   # use Apache to compress the results afterwards, to save on the wire
   # it's approx 18x savings of wire traffic to compress. We need to
   # compress by content types that htmlify can produce
-  AddOutputFilterByType DEFLATE text/plain text/html application/x-font-ttf
+  AddOutputFilterByType DEFLATE text/plain text/html application/x-font-ttf image/svg+xml
 
   <FilesMatch \.html\.gz$>
     ForceType text/html
@@ -37,6 +37,10 @@ NameVirtualHost <%= @vhost_name %>:<%= @port %>
     ForceType application/x-font-ttf
     AddEncoding x-gzip gz
   </FilesMatch>
+  <FilesMatch \.svg\.gz$>
+    ForceType image/svg+xml
+    AddEncoding x-gzip gz
+  </FilesMatch>
   <Directory <%= @docroot %>>
     Options <%= @options %>
     AllowOverride None