Remove outdated roadmap

roadmap.md

-# go-libp2p Q2 roadmap
-
-- [ ] websockets transport to communicate with js-ipfs
-- [ ] line switching for libp2p (relay)
-  - [ ] add config opt-in for relaying traffic
-  - [ ] add 'find indirect connections' logic to dht
-- [ ] Pubsub
-  - [ ] ship initial implementation to libp2p
-  - [ ] ipfs 'flare' in go-ipfs
-- [ ] NAT Traversal 
-  - [ ] Goal: No "I can't connect to my other node" issues for two weeks
-  - [ ] address discovery issue ipfs/#2509 ipfs/#2413
-  - [ ] testbed to simulate NAT scenarios
-  - [ ] command to clear dial backoff ipfs/#2456
-- [ ] libp2p connection closing
-  - [ ] figure out when we want to close connections
-  - [ ] select 'good' number of connections while idle (based on available resources?)
-- [ ] fix mocknet issues #31 #32