Added SIGTERM handling (same behavior as SIGINT)

As per http://en.wikipedia.org/wiki/Unix_signal:
SIGTERM
The SIGTERM signal is sent to a process to request its termination. Unlike the SIGKILL signal, it can be caught and interpreted or ignored by the process. This allows the process to perform nice termination releasing resources and saving state if appropriate. It should be noted that SIGINT is nearly identical to SIGTERM.