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/content-twat_episode.tpl.html

@@ -2,7 +2,7 @@
 <!--% PROCESS 'shared-avatar.tpl.html' %-->
 <!--% PROCESS 'shared-utils.tpl.html' %-->
 <!--% PROCESS 'shared-listen-now.tpl.html' %-->
-<!--% USE DBI(constants.driver, constants.user, constants.password) %-->
+<!--% USE DBI(constants.driver) %-->
 <!--% query_episodes = DBI.prepare('
 		WITH episode_maxmin AS (
 					SELECT MAX(id) AS \'latest\', MIN(id) AS \'earliest\', ? AS \'id\'