Try to write the plex_users table during config save.

Only load tables on user info page if we need to.
Make sure we don't pass user definable input directly into our queries.
Neaten some code.

plexpy/webserve.py

@@ -352,6 +352,9 @@ class WebInterface(object):
         # Write the config
         plexpy.CONFIG.write()
 
+        # Check if we have our users table
+        plexwatch.check_db_tables()
+
         # Reconfigure scheduler
         plexpy.initialize_scheduler()