pubspec name should use underscore rather than dash according to Dart Editor

According to Dart Editor version 1.1.1.release (STABLE), the pubspec name should use underscore rather than dash:
![image](https://f.cloud.github.com/assets/4140793/2030520/d37d9bee-88f7-11e3-8f31-e02de4084c00.png)

As seen from:
Dart Editor version 1.1.1.release (STABLE)
Dart SDK version 1.1.1