Implement HTMLTableElement.caption
Merge pull request #3098 from wenderen/HTMLTableElement.caption

implement GetCaption and SetCaption for HTMLTableElement; r=Manishearth
Update rust-azure to fix a dangling pointer bug

Fixes #3084
Merge pull request #3102 from dotdash/fixup_azure_lifetime_bug

Update rust-azure to fix a dangling pointer bug
Enable some of the HTML tests.