Add a reconnect mechanism to the MethodCall protocol

[Free Ekanayaka]

The MethodCall protocol what will be used for inter-process
communication between the various Landscape client components should be
robust enough to transparently:

1) Keep trying to connect if the very fist attempt failed (for instance the
   remote process we're trying to contact is not yet ready to accept
   connections).

2) Try to reconnect if the connection drops (for instance the remote
   process died and the watchdog started it again).

3) In case a MethodCall request failed because it was issued during a
   connection blackout (see 2), the protocol should try to perform it
   again as soon as the connection gets established again (for instance
   a monitor plugin tries to call a RemoteBroker.send_message while the
   broker is restarting).

 affects landscape-client
 status inprogress
 importance low
 assignee free.ekanayaka
 milestone 1.4.4

[Free Ekanayaka (free.ekanayaka)]

Tested on a not-yet-committed branch, that makes all services (watchdog, broker, monitor and manager) talk over AMP. I tried various combinations of killing the broker, the monitor and the manager, and the system resumes fine and correctly talks to the server (accepted types etc.).