Bump `package_config` to 1.0.0.

BUG=
R=lrn@google.com

Review URL: https://codereview.chromium.org//2061863002 .
diff --git a/CHANGELOG.md b/CHANGELOG.md
index b7b441e..18a42ce 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 1.0.0
+
+- Public API marked stable.
+
 ## 0.1.5
 
 - `FilePackagesDirectoryPackages.getBase(..)` performance improvements.
diff --git a/pubspec.yaml b/pubspec.yaml
index 3d9bd45..e1afec2 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: package_config
-version: 0.1.5
+version: 1.0.0 
 description: Support for working with Package Resolution config files.
 author: Dart Team <misc@dartlang.org>
 homepage: https://github.com/dart-lang/package_config