Remove active class from buttons.

refs #3989
- Remove active class from {{#link-to tagName="button" ..}}
Merge pull request #3991 from halfdan/3989-active-class

Remove active class from buttons
Improve keyboard support

issue #3964
- added :focus selector to improve keyboard support in modern browsers
- added :active selector to improve keyboard support in old IE
Merge pull request #3995 from JamieKnight/keyboard-support

Improve keyboard support
Post Settings Menu - Step 1

closes #3936
- Implement new PSM
- Hook up close action
- Automatically close when view is destroyed
- Close on click and when pressing ESC
Merge pull request #3965 from halfdan/3936-psm-1

PSM Step 1
Prevent horizontal scroll on content list

Closes #4000

- Adds `overflow-x: hidden;` to the content list & preview wrapper