Bumping to Slick 1.6.0 to fix some responsive issues

1.5.0

Updating to Slick 1.6.0 to fix some responsive bug

Fixing history.js dependencies

We were accidentally relying on other plugins to pull in native.history.js, which is used in the gallery plugin. We added the dependency in the grunt build, which also added native.history.js into the dist folder and into the bower.json main entry so it gets copied into your project.