Tried to reduce the opacity of the header bottom-border some to make it seem less intense. Want to get some feedback. Also added a box-shadow to the tags to smooth out the edges (something we've done at raintank)

Select form updates

Update kbn.js - correct typo for megabits/sec

some nav fixes

ux(): fixed sidemenu submenu hover issue that caused it to be hidden as the mouse tried to move on to the submenu

Conflicts:
	public/sass/_grafana.scss

Conflicts:
	public/sass/.sass-lint.yml
	tasks/options/sasslint.js