Responsive changes - more tablet functionality

Removed .hidden-sm in both controls div and weekdays ul so that tablet users can control the calendar and see weekdays above the calendar.
SCSS re-compilation - new CSS code
Utilized new SCSS media-query breakpoint variable

Instead of hard-coding in the breakpoint, the media-query breakpoint variable provided in our _global SCSS file was used for easier mantainability.
Added "upto" SCSS media-query breakpoints

Added new "upto" SCSS media-query breakpoints for the most amount of control when coding in CSS. For ex, $screen-xs-upto is a media-query breakpoint that will style anything below tablets. $screen-sm-upto will style tablets and anything below tablets. $screen-md-upto will style old desktop/laptop screen sizes, tablets, and other form factors below these sizes (phones)