v3.1.1 bump
update homepage showcase with three new posts
grunt
grunt
Update less.js to v1.6.3.
Update dependencies.
Merge pull request #12718 from twbs/dependencies

Update dependencies.
Merge pull request #12719 from twbs/update-less

Update less.js to v1.6.3.
Add build-raw-files log; fixes #12603

Fixes #12672