First pass at migrating to universal analytics.
customize tracking code
add second tracker
Merge pull request #331 from dart-lang/ua

WIP: New analytics code
Fixed analytics script
Added documentation about the CHANGELOG.md file
Merge pull request #332 from Scorpiion/master

Added documentation about the CHANGELOG.md file
Updating the docgen page.

BUG=
R=kevmoo@google.com

Review URL: https://codereview.appspot.com/99040043
Removed duplicate link to markdown site
Merge pull request #333 from Scorpiion/master

Removed duplicate link to markdown site
Add breadcrumbs to tool and article pages

Staged at:
https://bc-dot-dart-lang.appspot.com/tools/pub/

Review URL: https://chromiumcodereview.appspot.com/271003002
Be more clear about what we support
Merge pull request #335 from sethladd/master

Be more clear about what we support
Fix the "Custom attribute" description

R=sigmund@google.com

Review URL: https://chromiumcodereview.appspot.com/283983002
Removed section about doc-code-verify
Fixing bug 16931.

BUG=
R=danrubel@google.com

Review URL: https://codereview.appspot.com/95500045