Add first changes to syncing logic

- Adds testing framework
- Breaks out new `NetworkContext` object

beacon_node/network/Cargo.toml

@@ -4,6 +4,10 @@ version = "0.1.0"
 authors = ["Age Manning <Age@AgeManning.com>"]
 edition = "2018"
 
+[dev-dependencies]
+test_harness = { path = "../beacon_chain/test_harness" }
+sloggers = "0.3.2"
+
 [dependencies]
 beacon_chain =  { path = "../beacon_chain" }
 libp2p =  { path = "../libp2p" }