Remove MySQL specific code from site generation code

- site-generator is generic, so no changes.
 - removed mysql information from site.cfg.
 - Updated template files to call sqlite queries directly.
 - Renamed the query files - remove sqlite from file names.
 - Deleted MySQL specific template files.

templates/rss-hpr.tpl.xml

@@ -1,5 +1,5 @@
 <!--% PROCESS 'shared-item.tpl.xml' %-->
-<!--% PROCESS "rss-query-hpr-${constants.database}.tpl.xml" %-->
+<!--% PROCESS "rss-query-hpr.tpl.xml" %-->
 <!--% FOREACH episode IN feed_result %-->
 <!--% display_item(episode, media_file_extension, audio_mime_type) %-->
 <!--% END %-->