Added further tests for navigation

README.md

lib/tasks/tests/visual/generate.js

lib/tasks/tests/visual/session.js

material/assets/stylesheets/application-166740f5bb.css

material/base.html

src/assets/stylesheets/layout/_nav.scss

...v--primary/md-nav__item--nested/md-nav/@screen/chrome.png

...nav--primary/md-nav__item--nested/md-nav/@screen/edge.png

...--primary/md-nav__item--nested/md-nav/@screen/firefox.png

...nav--primary/md-nav__item--nested/md-nav/@screen/ie11.png

.../md-nav__item--nested/md-nav/@tablet-landscape/chrome.png

...ry/md-nav__item--nested/md-nav/@tablet-landscape/edge.png

...md-nav__item--nested/md-nav/@tablet-landscape/firefox.png

...ry/md-nav__item--nested/md-nav/@tablet-landscape/ie11.png

...-nested/md-nav/md-nav__title/@tablet-landscape/chrome.png

...m--nested/md-nav/md-nav__title/@tablet-landscape/edge.png

...nested/md-nav/md-nav__title/@tablet-landscape/firefox.png

...m--nested/md-nav/md-nav__title/@tablet-landscape/ie11.png

...-nav/md-nav__title/~overflow/@tablet-landscape/chrome.png

...md-nav/md-nav__title/~overflow/@tablet-landscape/edge.png