Support latest pkg/build (#90)

Author: kevmoo

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.5.1+1
+
+* Support the latest version of `build` package.
+
 ## 0.5.1
 
 * Added GeneratorBuilder option isStandalone to generate files that aren't 

pubspec.yaml

@@ -1,17 +1,17 @@
 name: source_gen
-version: 0.5.1
+version: 0.5.1+1
 author: Dart Team <[email protected]>
 description: Automatic sourcecode generation for Dart
 homepage: https://github.com/dart-lang/source_gen
 environment:
   sdk: '>=1.12.0 <2.0.0'
 dependencies:
   analyzer: '^0.27.3'
-  build: '>=0.2.1 <0.4.0'
+  build: '>=0.2.1 <0.5.0'
   cli_util: ^0.0.1
   dart_style: '>=0.1.7 <0.3.0'
   path: ^1.3.2
 dev_dependencies:
   collection: ^1.1.2
-  mockito: ^0.11.0
+  mockito: '>=0.11.0 <2.0.0'
   test: ^0.12.3