Support embedded full/light node clients. (#91)

* Add support for light clients.

* Add wasm toolchain to ci.

* Fix ci tests.

* Address review comments.

* Use expect instead of unwrap.

* Purge light client chain too.

* Add README section.

client/Cargo.toml

@@ -0,0 +1,30 @@
+[package]
+name = "substrate-subxt-client"
+version = "0.1.0"
+authors = ["David Craven <david@craven.ch>", "Parity Technologies <admin@parity.io>"]
+edition = "2018"
+
+license = "GPL-3.0"
+repository = "https://github.com/paritytech/substrate-subxt"
+documentation = "https://docs.rs/substrate-subxt-client"
+homepage = "https://www.parity.io/"
+description = "Embed a substrate node into your subxt application."
+keywords = ["parity", "substrate", "blockchain"]
+
+[dependencies]
+async-std = "=1.5.0"
+futures = { version = "0.3.5", features = ["compat"] }
+futures01 = { package = "futures", version = "0.1.29" }
+jsonrpsee = "0.1.0"
+log = "0.4.8"
+sc-network = { version = "0.8.0-rc3", default-features = false }
+sc-service = { version = "0.8.0-rc3", default-features = false }
+serde_json = "1.0.53"
+sp-keyring = "2.0.0-rc3"
+thiserror = "1.0.19"
+
+[dev-dependencies]
+async-std = { version = "=1.5.0", features = ["attributes"] }
+env_logger = "0.7.1"
+node-template = { git = "https://github.com/paritytech/substrate" }
+substrate-subxt = { path = ".." }