Initial content revisions for site reorg.
Merge branch 'master' of https://github.com/Polymer/docs into wc-reorg

Conflicts:
	docs/start/getting-the-code.md
	docs/start/platform.md
	docs/start/usingelements.md
Content updates for site reorg.
Merge branch 'master' of https://github.com/Polymer/docs into wc-reorg
Merge branch 'master' of https://github.com/Polymer/docs into wc-reorg

Conflicts:
	elements/docs-menu.html
Add redirect for old custom elements 101 doc.
More cleanup.
Merge pull request #756 from arthurevans/wc-reorg

Content updates for WC reorg