Fix incorrect sort on haproxy backends

This bug caused that haproxy backend names would not match the actual
haproxy backend ip:port address.
Add support for multiple haproxy admin sockets

When haproxy is used with nbproc > 1 the proper operation requires
that each process has its own admin socket. This can be done wiht
this kind of config:

     stats socket /var/run/haproxy/admin1.sock level admin user haproxy group haproxy process 1
     stats socket /var/run/haproxy/admin2.sock level admin user haproxy group haproxy process 2
     stats socket /var/run/haproxy/admin3.sock level admin user haproxy group haproxy process 3
     nbproc 3

With this patch the admin socket can have path wildcards and
all enable/disable commands are run to every admin socket.