[dependencies] bump rand 0.7 (#11022)

* network-devp2p: bump rand `0.7`

* updater: bump rand `0.7`

* hash-fetch: bump rand `0.7`

* ethcore-sync: bump rand `0.7`

* rpc: dont work yet

* [private-tx] remove unused rand

* [ethcore-snapshot] bump rand 0.7

* [engine clique]: bump rand 0.7

* [engine authority-round]: remove rand

* [ethcore-blockchain]: bump rand 0.7

* [ethcore]: bump rand 0.7

* [ethcore-light]: bump rand 0.7

* [ethstore]: bump rand 0.7

* Fix for rand usage in rpc

* [rpc]: fix test build

* [ethcore-sync]: fix test build

* [snapshot tests]: rand 0.7

* [ethkey]: bump rand 0.7

* [rpc]: resolve TODO incompatible `rand versions`

* [ethkey] use `rust-secp256k1` master branch

* fix(bad merge): ethcoore-light remove itertools

* [rpc tests]: revert rpc test changes in #11139

`#11139` makes use a different `RNG/seed`, not `H64::random_using(&mut self.rand)`

This commit reverts the changed tests (the generated id by `Subscribers::next_id`)

* [ethkey/random]: resolve introduced `TODO`

ethcore/sync/src/light_sync/mod.rs

@@ -716,7 +716,7 @@ impl<L: AsLightClient> LightSync<L> {
 			peers: RwLock::new(HashMap::new()),
 			pending_reqs: Mutex::new(HashMap::new()),
 			client: client,
-			rng: Mutex::new(OsRng::new()?),
+			rng: Mutex::new(OsRng),
 			senders: RwLock::new(Vec::new()),
 			state: Mutex::new(SyncStateWrapper::idle()),
 			is_idle: Mutex::new(true),