health: Reporting initial VM affinity to a file

When the hosts are connected, let's print the initial affinity in a
specific file. This could be easier to debug some issues in the affinity
placement.

A sample output looks like the following:
[erwan@localhost src (master)]$ cat /home/erwan/Devel/edeploy/health/dahc/all_load/2014_09_22-15h13/affinity
{'44454c4c-4b00-1039-8050-b9c04f573032': [('127.0.0.1', 56459),
                                          ('127.0.0.1', 56458)],
 '44454c4c-4b00-1039-8056-b9c04f573032': [('127.0.0.1', 56457),
                                          ('127.0.0.1', 56456)]}