Add set_signal_map to utils.

cloudcontrol/node/utils.py

 import os
 import sys
 import errno
+import signal
 import resource
 import subprocess
 from collections import deque
@@ -137,3 +138,17 @@ def close_fds(exclude_fds=None, debug=False):
         assert sys.stdin.fileno() == 0
         assert sys.stdout.fileno() == 1
         assert sys.stderr.fileno() == 2
+
+
+def set_signal_map(map_):
+    """Set signal map in fork children.
+
+    :param mapping map_: (signal code, handler)...
+    :returns: old handlers as dict
+    """
+    previous_handlers = dict()
+
+    for sig, handler in map_.iteritems():
+        previous_handlers[sig] = signal.signal(sig, handler)
+
+    return previous_handlers