Slide out tab SCSS: Moved placeholder selector declaration into @media screen type.
Resolves SASS deprecation warnings when building.
Merge pull request #2947 from EricDunsworth/v3.1-slideout-placeholder-location

Slide out tab SCSS: Moved placeholder selector declaration into @media screen type.
Themes: Fixed terms and conditions comment in the SVG files.
Merge pull request #2948 from pjackson28/fixsvgterms

Themes: Fixed terms and conditions comment in the SVG files.
Gitignore file: Added lib folder.
Merge pull request #2954 from EricDunsworth/v3.0-gitignore-lib

Gitignore file: Added lib folder.
Build: Switch to JSHint RC file

- Based off of jQuery recommendation except double quotemark
- The ant task also doesn't support the "globals" property in the JSON
file
Grids SCSS: Disabled link icons in secondary menus.

Fixes #2364
Closes #2953
Linting: Trim trailing space
Linting: cleanup unused variable warnings
Linting: Enforce onevar option
Linting; Remove pe and jQuery globals

Replaced with jquery JSHint option and the "browser" option for the
theme references to window.
"pe" global only kept for the themes and polyfill where they don't use
the "_pe" cached version
Build: Add jshintignore for CLI based linting
Merge pull request #2957 from nschonni/jshint-dotfiles

Linting
Resolved merge conflicts.