Added build.dart to make Polymer iterations in Dart Editor easier.

Essentially just pulls in the changes under widgets/ into ide/app/packages, allowing quick debugging of the uncompiled app.

Still needs to be run manually every time 'widgets/' change, but that can be done via the context menu or Run button of the editor without switching to command line and back.
nits
Merge pull request #107 from ussuri/fix-polymer-stuff

Adjusted to the new way Polymer elements have to be defined.
Merge pull request #108 from dart-lang/cleanups

nits
Merge pull request #112 from ussuri/ui-cleanups

Equalize the height of some UI elements
Addressed comments
Merge pull request #110 from ussuri/add-build-dart

Added build.dart to make Polymer iterations in Dart Editor easier.
Addressed comments
Attempt to go back to CRLF line endings to appease github's diff.
Addressed comments
Micro-improvement

...In light of recent discussion re: braces with control statements (in some pull request).
Merge pull request #111 from ussuri/context-menu-ui-switching

Context menu ui switching
Unimportant UI improvement
Moved a general utility function to utils.dart
Merge pull request #113 from ussuri/add-spark-select

Add <spark-select> custom Polymer element to widgets/
Merge pull request #114 from ussuri/polymer-theme-chooser

Polymer theme chooser
Fixed UI switching via context menu
Merge pull request #115 from ussuri/fix-ui-switching

Fixed UI switching via context menu