LP#1485371: Use client-supplied TZ

LP#1485371: Use client-supplied TZ

Currently, there is no protocol-level mechanism for passing the client's
desired timezone to the server. In much the same way we pass the locale,
we can let the server know what timezone it should use when interpreting
time stamps.

To do this we:

 * Teach perl server code to live in the client TZ, if supplied
 * Teach perl client code to send the current $ENV{TZ}
 * Teach javascript library to include client TZ in
   gateway/translator/websocket communication
 * Teach C code to pull the incoming TZ and apply it to outgoing messages
 * Teach srfsh to pull TZ from the environment and pass it with requests

Signed-off-by: Mike Rylander <mrylander@gmail.com>