Chutney generates network with no bandwidth weights

Hello,

when chutney makes a Tor network, it sets the following options in the dirauth torrc:

TestingDirAuthVoteExit *
TestingDirAuthVoteGuard *

which results in a network where all nodes are guards and exits.

This results in totally unbalanced bandwidths (0 guard bandwidth, 0 middle bandwidth, full guard+exit bandwidth) and authorities will not generate bandwidth weights:

[warn] Consensus with empty bandwidth: G=0 M=0 E=0 D=65770 T=65770

This is quite different from the real Tor network.

It would be great if chutney could assign Exit/Guard flag in a smarter way to only a few nodes, so that bandwidth can be allocated more widely.