Enable use of WS API Security Pin

Enabling the Security Pin parameter for /Myth/GetConnectionInfo when connecting to the WS API on the backend. The security pin on separate backends must be the same. Entering 0000 is a valid PIN. And a security pin must be configured with mythtv-setup before any API access can work, as noted before in this post: http://forum.kodi.tv/showthread.php?tid=198833&pid=1743105#pid1743105