Part of an update to align the naming schemes across our components.

- Renames .popover-title to .popover-header
- Renames .popover-content to .popover-body

Refs: #22092

* Update Dependencies (REUPLOAD)

Uglify-JS: 2.8.22 > 3.0.3
QUnitJS: 2.3.1 > 2.3.2
PostCSS-CLI: 3.1.1 > 4.0.0
Clean-CSS-CLI: 4.0.12 > 4.1.0
Babel-Eslint: 7.2.2 > 7.2.3
AutoPrefixer: 6.7.7 > 7.0.1

* Updates More Dependencies

Autoprefixer: v7.0.1 > v7.1.1
Clean-CSS-CLI: v4.1.0 > v4.1.3
Node-Sass: v4.5.2 > v4.5.3
PostCSS-FlexBugs-Fixes: v2.1.1 > v3.0.0
Uglify-JS: v3.0.3 > v3.0.11
Signed-off-by: CDAGaming <cstack2011@yahoo.com>

* Update Gem Bundler Dependency

Signed-off-by: CDAGaming <cstack2011@yahoo.com>

* Update Gemfile.lock Dependency

Signed-off-by: CDAGaming <cstack2011@yahoo.com>

* Update QUnit

Signed-off-by: CDAGaming <cstack2011@yahoo.com>

* Update Uglify-JS to v3.0.13

Signed-off-by: CDAGaming <cstack2011@yahoo.com>

According to the docs, you just need to apply the `navbar-nav` to an
`<ul>` tag in a list-based navbar. In fact, `navbar-nav` seems to
override all the css properties set by `nav`.

Also, `nav-item` class should be used only for `<li>` tags, or in
conjunction with `<a>` tags to entirely avoid the list-based approach.

This commit removes the redundant `nav` class from `navbar-nav` `<ul>`
tags, moves `nav-item` from `<a>` tags to `<li>` tags and properly
adds `nav-item` class to `<li>` tags where missing.

Refs:

* https://v4-alpha.getbootstrap.com/components/navs/
* https://v4-alpha.getbootstrap.com/components/navbar/#nav