fixes #13216

change `@zindex-popover` and `@zindex-tooltip` values to be greater than
those set for `@zindex-modal` allowing tooltips and popovers to be
displayed in front of modals (and all other content).
Merge pull request #13217 from thedavidscherer/fix-13216

fixes #13216
Update dependencies.
Fix the new JSHint warnings.
Run `grunt`.