pkg/docgen: updated min dependencies of args and unittest

pkg/docgen/pubspec.yaml

 name: docgen
-version: 0.9.1
-author: "Dart Team <misc@dartlang.org>"
+version: 0.9.2-dev
+author: Dart Team <misc@dartlang.org>
+description: A documentation generator for the Dart repository.
 homepage: https://github.com/dart-lang/dartdoc-viewer
-description: A documentation generator for the Dart repository.
+environment:
+  sdk: '>=0.8.10+6 <2.0.0'

[Alan Knight, 2014/02/19 19:00:46]

I doubt that minimum constraint is valid, but it probably doesn't really matter
because people will use the snapshot, so it's locked to the SDK.

 dependencies:
-  args: ">=0.9.0 <0.10.0"
-  logging: ">=0.9.0 <0.10.0"
+  args: '>=0.9.0 <0.11.0'
+  logging: '>=0.9.0 <0.10.0'
   markdown:
     git:
       ref: emilysEdits
       url: https://github.com/efortuna/dart-markdown
-  path: ">=0.9.0 <2.0.0"
-  yaml: ">=0.9.0 <0.10.0"
+  path: '>=0.9.0 <2.0.0'
+  yaml: '>=0.9.0 <0.10.0'
 dev_dependencies:
-  unittest: ">=0.9.0 <0.10.0"
-environment:
-  sdk: ">=0.8.10+6 <2.0.0"
+  unittest: '>=0.9.0 <0.11.0'