[BREAKING] Fix inconsistencies with col viewport classes and the rest of the framework

[Spiderpig86]

• For example, col-xs-2 applies to 641px to 768px instead of 0px to 640px like the rest of the framework.
• To fix, we need to switch to using breakpoint pairs which would effectively bump all the viewports down by 1.
• This will be a high-impact change.