wicd-daemon assumes DBUS is up and running w/o checking

[nbernhardt]

The daemon script wicd-daemon.py does not check if system_bus_socket is already up. On some system this leads to the situation where DBUS is still 'at work' starting up, the socket not yet running, and wicd fails with:
File "/usr/share/wicd/daemon/wicd-daemon.py", line 1914, in main
     bus = dbus.SystemBus()
…
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.FileNotFound: Failed to connect to socket /var/run/dbus/system_bus_socket: No such file or directory

There should be some check before invoking DBUS, if not wait for some seconds, then bail out.

wicd is version 1.7.4 961

Distro is PCLinuxOS latest version.