Use a realistic test network w/ DHT

[hannahhoward]

Goals

Setup benchmarks that more closely approximate conditions of real IPFS usage -- namely, a real DHT and real provider queries

Implementation

• Modify StreamNet to allow configuring it with either mock routing or a real Kademlia DHT
• Create a new bench mark pattern that sets up a mock net, where not all nodes are connected to one another initially (and can be connected in a variety of patterns), where some nodes have some blocks and announce what blocks they have to the DHT, and test one peer attempts to fetch the blocks from others
• See benchmarks_test.go for this implementation. Probably can use some cleanup -- and the node counts right now are low specifically because the DHT is not fast -- but not even under these conditions the test takes a lot longer than w/o a DHT and with all nodes connected immediately