Support Intra-Domain Topology for ASes

[amdfxlucas]

This issue was originally opened on SEED seed-labs#177 but was ignored.

In a nutshell:

realistic network simulations require a realistic topology, so most simulators allow to read it from file.
There are various formats output by different topology generators i.e. :

• BRITE
• INET
• CAIDA
• ORBIS