avocado.job: Properly handle Ctrl+C inside avocado

Handle KeyboardInterrupt inside avocado, making
Ctrl+C to terminate the program, instead of generating
a python backtrace.
Signed-off-by: NLucas Meneghel Rodrigues <lmr@redhat.com>

avocado/job.py

@@ -126,10 +126,15 @@ class TestRunner(object):
             e_msg = "Timeout reached waiting for %s to end" % instance
             raise exceptions.TestTimeoutError(e_msg)
 
+        def interrupt_handler(signum, frame):
+            e_msg = "Test %s interrupted by user" % instance
+            raise exceptions.TestInterruptedError(e_msg)
+
         instance = self.load_test(params)
         queue.put(instance.get_state())
 
         signal.signal(signal.SIGUSR1, timeout_handler)
+        signal.signal(signal.SIGINT, interrupt_handler)
 
         self.result.start_test(instance.get_state())
         try:
@@ -431,6 +436,12 @@ class Job(object):
         except exceptions.OptionValidationError, details:
             self.output_manager.log_fail_header(str(details))
             return error_codes.numeric_status['AVOCADO_JOB_FAIL']
+        except KeyboardInterrupt:
+            for child in multiprocessing.active_children():
+                os.kill(child.pid, signal.SIGINT)
+            self.output_manager.log_header('\n')
+            self.output_manager.log_header('Interrupted by user request')
+            sys.exit(error_codes.numeric_status['AVOCADO_JOB_FAIL'])
 
         except Exception, details:
             self.status = "ERROR"