chore: cut the 0.4.0 release

Cut the 0.4.0 release.
Update version in `Cargo.toml` and `README.md`.
Update `CHANGELOG.md`.

CHANGELOG.md

@@ -1,3 +1,13 @@
+<a name="v0.5.0"></a>
+## v0.5.0 (2016-12-08)
+
+
+#### Features
+
+*   add borrow_with to LazyCell ([a15efa35](https://github.com/indiv0/lazycell/commit/a15efa359ea5a31a66ba57fc5b25f90c87b4b0dd))
+
+
+
 <a name="v0.4.0"></a>
 ##  (2016-08-17)
 

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "lazycell"
-version = "0.4.0"
+version = "0.5.0"
 authors = ["Alex Crichton <alex@alexcrichton.com>",
            "Nikita Pekin <contact@nikitapek.in>"]
 description = "A library providing a lazily filled Cell struct"

README.md

@@ -34,7 +34,7 @@ Add the following to your `Cargo.toml`:
 
 ```toml
 [dependencies]
-lazycell = "0.4"
+lazycell = "0.5"
 ```
 
 And in your `lib.rs` or `main.rs`: