Rewrite using tokio (#44)

* Rewrite tarpc on top of tokio.

* Add examples

* Move error types to their own module.

Also, cull unused error variants.

* Remove unused fn

* Remove CanonicalRpcError* types. They're 100% useless.

* Track tokio master (WIP)

* The great error revamp.

Removed the canonical rpc error type. Instead, the user declares
the error type for each rpc:

In the above example, the error type is Baz. Declaring an error is
optional; if none is specified, it defaults to Never, a convenience
struct that wraps the never type (exclamation mark) to impl Serialize, Deserialize,
Error, etc. Also adds the convenience type StringError for easily
using a String as an error type.

* Add missing license header

* Minor cleanup

* Rename StringError => Message

* Create a sync::Connect trait.

Along with this, the existing Connect trait moves to future::Connect. The future
and sync modules are reexported from the crate root.

Additionally, the utility errors Never and Message are no longer reexported from
the crate root.

* Update readme

* Track tokio/futures master. Add a Spawn utility trait to replace the removed forget.

* Fix pre-push hook

* Add doc comment to SyncServiceExt.

* Fix up some documentation

* Track tokio-proto master

* Don't set tcp nodelay

* Make future::Connect take an associated type for the future.

* Unbox FutureClient::connect return type

* Use type alias instead of newtype struct for ClientFuture

* Fix benches/latency.rs

* Write a plugin to convert lower_snake_case idents/types to UpperCamelCase.

Use it to add associated types to FutureService instead of boxing the return futures.

* Specify plugin = true in snake_to_camel/Cargo.toml. Weird things happen otherwise.

* Add clippy.toml

hooks/pre-commit

@@ -89,22 +89,23 @@ fi
 # not only contain discrete files.
 printf "${PREFIX} Checking formatting ... "
 FMTRESULT=0
+diff=""
 for file in $(git diff --name-only --cached);
 do
 	if [ ${file: -3} == ".rs" ]; then
-        diff=$(rustfmt --skip-children --write-mode=diff $file)
-        if grep --quiet "^Diff at line" <<< "$diff"; then
-			FMTRESULT=1
-		fi
+        diff="$diff$(rustfmt --skip-children --write-mode=diff $file)"
 	fi
 done
+if grep --quiet "^Diff at line" <<< "$diff"; then
+    FMTRESULT=1
+fi
 
 if [ "${TARPC_SKIP_RUSTFMT}" == 1 ]; then
 	printf "${SKIPPED}\n"$?
 elif [ ${FMTRESULT} != 0 ]; then
 	FAILED=1
 	printf "${FAILURE}\n"
-    echo "$diff" | sed '/Using rustfmt.*$/d'
+    echo "$diff" | sed 's/Using rustfmt config file.*$/d/'
 else
 	printf "${SUCCESS}\n"
 fi