Update to tokio 1.1 (#2172)

## Issue Addressed

resolves #2129
resolves #2099 
addresses some of #1712
unblocks #2076
unblocks #2153 

## Proposed Changes

- Updates all the dependencies mentioned in #2129, except for web3. They haven't merged their tokio 1.0 update because they are waiting on some dependencies of their own. Since we only use web3 in tests, I think updating it in a separate issue is fine. If they are able to merge soon though, I can update in this PR. 

- Updates `tokio_util` to 0.6.2 and `bytes` to 1.0.1.

- We haven't made a discv5 release since merging tokio 1.0 updates so I'm using a commit rather than release atm. **Edit:** I think we should merge an update of `tokio_util` to 0.6.2 into discv5 before this release because it has panic fixes in `DelayQueue`  --> PR in discv5:  https://github.com/sigp/discv5/pull/58

## Additional Info

tokio 1.0 changes that required some changes in lighthouse:

- `interval.next().await.is_some()` -> `interval.tick().await`
- `sleep` future is now `!Unpin` -> https://github.com/tokio-rs/tokio/issues/3028
- `try_recv` has been temporarily removed from `mpsc` -> https://github.com/tokio-rs/tokio/issues/3350
- stream features have moved to `tokio-stream` and `broadcast::Receiver::into_stream()` has been temporarily removed -> `https://github.com/tokio-rs/tokio/issues/2870
- I've copied over the `BroadcastStream` wrapper from this PR, but can update to use `tokio-stream` once it's merged https://github.com/tokio-rs/tokio/pull/3384

Co-authored-by: realbigsean <seananderson33@gmail.com>

beacon_node/http_api/Cargo.toml

@@ -5,9 +5,11 @@ authors = ["Paul Hauner <paul@paulhauner.com>"]
 edition = "2018"
 
 [dependencies]
-warp = { git = "https://github.com/sigp/warp ", branch = "lighthouse" }
+warp = "0.3.0"
 serde = { version = "1.0.116", features = ["derive"] }
-tokio = { version = "0.3.2", features = ["macros","stream","sync"] }
+tokio = { version = "1.1.0", features = ["macros","sync"] }
+tokio-stream = "0.1.2"
+tokio-util = "0.6.3"
 parking_lot = "0.11.0"
 types = { path = "../../consensus/types" }
 hex = "0.4.2"
@@ -32,5 +34,4 @@ futures = "0.3.8"
 store = { path = "../store" }
 environment = { path = "../../lighthouse/environment" }
 tree_hash = "0.1.1"
-discv5 = { version = "0.1.0-beta.2", features = ["libp2p"] }
-tokio-compat-02 = "0.1"
+discv5 = { version = "0.1.0-beta.3" }