Add delays between container groups (more of an enhacement)

[gtato]

In the context of distributed services it would be nice to simulate different latencies between groups of containers. For example, instead of providing the filtering IP and list of containers, the user can provide a graph file where different groups are defined

pumba netem delay --graph graphfile

and the graph file can be something like this

groups:
    group_1:
        container_1_1 
        container_1_2 
    group_2:
        container_2_1 
        container_2_2
        ip_2_3 # you can support both IPs and container names 
    group_3:
        container_3_1 

filters: 
   filter_1:
       src_group: group_1
       dst_group: group_2
       delay: 150
   filter_2:
       src_group: group_1
       dst_group: group_3
       delay: 250

[alexei-led]

@gtato nice idea, need to think... and create well-defined spec. Want to contribute spec or/and code as PR?