Data binding doc update, at last. Note: requires redirect for filters.html
Merge branch 'master' of https://github.com/Polymer/docs into binding-examples

Conflicts:
	docs/polymer/expressions.md
	elements/docs-menu.html
Fixed import path
Minor fixes to scoping & one typo
Add outer template in scoping example, fixed typo.
Updated to address comments.
Fixed polymer-body heading title
Merge pull request #374 from arthurevans/databinding-update

Databinding update