mgmt: Reinitialize multicast faces and partially reload config file on HUP signal

The following elements from the config file are reloaded:
- effective user/group
- log levels
- multicast faces (enable/disable)
- security

Change-Id: I6ddf124702b30610dd0404d8fbaa9a9d800f02bf
Refs: #1584
diff --git a/daemon/face/udp-channel.hpp b/daemon/face/udp-channel.hpp
index 73403aa..4db6e43 100644
--- a/daemon/face/udp-channel.hpp
+++ b/daemon/face/udp-channel.hpp
@@ -74,6 +74,10 @@
    * \param onFaceCreated  Callback to notify successful creation of the face
    * \param onAcceptFailed Callback to notify when channel fails
    *
+   * Once a face is created, if it doesn't send/receive anything for
+   * a period of time equal to timeout, it will be destroyed
+   * \todo this functionality has to be implemented
+   *
    * \throws UdpChannel::Error if called multiple times
    */
   void