Filter and reorder controls in a menu bar

- Add menu bar area to primary card
- add Bartender module for building filter/sort menu (get it? it shakes
and strains)
- Add %fixFlagContainer extendible SCSS classes for fixing tags/buttons
that have .flag in some browsers
- Move .tag and .byline spacing to the .card module
- Add a bunch of libraries: Drop (and Tether) libraries, underscore
string, Velocity animations, Velocity UI
- Simple theme for Drop drop down content menu
- Add .horizontal class for .menu module
- tweak to grid layout for IE10/11
- icons for sorting and filtering in menu bar
- Modify main header layout to reflect slight change in .menu css

Related to issue #8