[polymer & pkgs] update pubspecs to prepare for -pre.0 release

pkg/observe/pubspec.yaml

 name: observe
-version: 0.10.0-dev
+version: 0.10.0-pre.0
 author: Polymer.dart Authors <web-ui-dev@dartlang.org>
 description: >
-  Observable properties and objects for use in Model-Driven-Views (MDV).
-  MDV extends HTML and the DOM APIs to support a sensible separation between the
-  UI (DOM) of a document or application and its underlying data (model).
-  Updates to the model are reflected in the DOM and user input into the DOM is
-  immediately assigned to the model.
+  Observable properties and objects for use in template_binding.
+  Template Binding extends HTML and the DOM APIs to support a sensible
+  separation between the UI (DOM) of a document or application and its
+  underlying data (model). Updates to the model are reflected in the DOM and
+  user input into the DOM is immediately assigned to the model.
 homepage: https://www.dartlang.org/polymer-dart/
 dependencies:
-  analyzer: ">=0.10.1 <0.11.0"
+  analyzer: ">=0.12.2 <0.13.0"
   barback: ">=0.9.0 <0.13.0"
   logging: ">=0.9.0 <0.10.0"
   path: ">=0.9.0 <2.0.0"
-  smoke: ">=0.1.0-dev <0.2.0"
+  smoke: ">=0.1.0-pre.0 <0.2.0"
   source_maps: ">=0.9.0 <0.10.0"
 dev_dependencies:
-  unittest: ">=0.9.0 <0.10.0"
+  unittest: ">=0.10.0 <0.11.0"
 environment:
-  sdk: ">=1.0.0 <2.0.0"
+  sdk: ">=1.2.0 <2.0.0"