Migrate actix-net to std::future (#64)

* Migrate actix-codec, actix-rt, and actix-threadpool to std::future

* update to latest tokio alpha and futures-rs

* Migrate actix-service to std::future,

This is a squash of ~8 commits, since it included a lot of experimentation. To see the commits,
look into the semtexzv/std-future-service-tmp branch.

* update futures-rs and tokio

* Migrate actix-threadpool to std::future (#59)

* Migrate actix-threadpool to std::future

* Cosmetic refactor

- turn log::error! into log::warn! as it doesn't throw any error
- add Clone and Copy impls for Cancelled making it cheap to operate with
- apply rustfmt

* Bump up crate version to 0.2.0 and pre-fill its changelog

* Disable patching 'actix-threadpool' crate in global workspace as unnecessary

* Revert patching and fix 'actix-rt'

* Migrate actix-rt to std::future (#47)

* remove Pin from Service::poll_ready(); simplify combinators api; make code compile

* disable tests

* update travis config

* refactor naming

* drop IntoFuture trait

* Migrate actix-server to std::future (#50)

Still not finished, this is more WIP, this is an aggregation of several commits, which
can be found in semtexzv/std-future-server-tmp branch

* update actix-server

* rename Factor to ServiceFactory

* start server worker in start mehtod

* update actix-utils

* remove IntoTransform trait

* Migrate actix-server::ssl::nativetls to std futures (#61)

* Refactor 'nativetls' module

* Migrate 'actix-server-config' to std futures

- remove "uds" feature
- disable features by default

* Switch NativeTlsAcceptor to use 'tokio-tls' crate

* Bikeshed features names and remove unnecessary dependencies for 'actix-server-config' crate

* update openssl impl

* migrate actix-connect to std::future

* migrate actix-ioframe to std::future

* update version to alpha.1

* fix boxed service

* migrate server rustls support

* migratte openssl and rustls connecttors

* store the thread's handle with arbiter (#62)

* update ssl connect tests

* restore service tests

* update readme

actix-utils/src/counter.rs

@@ -1,7 +1,8 @@
 use std::cell::Cell;
 use std::rc::Rc;
+use std::task;
 
-use futures::task::AtomicTask;
+use crate::task::LocalWaker;
 
 #[derive(Clone)]
 /// Simple counter with ability to notify task on reaching specific number
@@ -12,7 +13,7 @@ pub struct Counter(Rc<CounterInner>);
 struct CounterInner {
     count: Cell<usize>,
     capacity: usize,
-    task: AtomicTask,
+    task: LocalWaker,
 }
 
 impl Counter {
@@ -21,7 +22,7 @@ impl Counter {
         Counter(Rc::new(CounterInner {
             capacity,
             count: Cell::new(0),
-            task: AtomicTask::new(),
+            task: LocalWaker::new(),
         }))
     }
 
@@ -32,8 +33,8 @@ impl Counter {
 
     /// Check if counter is not at capacity. If counter at capacity
     /// it registers notification for current task.
-    pub fn available(&self) -> bool {
-        self.0.available()
+    pub fn available(&self, cx: &mut task::Context) -> bool {
+        self.0.available(cx)
     }
 
     /// Get total number of acquired counts
@@ -66,15 +67,15 @@ impl CounterInner {
         let num = self.count.get();
         self.count.set(num - 1);
         if num == self.capacity {
-            self.task.notify();
+            self.task.wake();
         }
     }
 
-    fn available(&self) -> bool {
+    fn available(&self, cx: &mut task::Context) -> bool {
         if self.count.get() < self.capacity {
             true
         } else {
-            self.task.register();
+            self.task.register(cx.waker());
             false
         }
     }