slight cleanup

removed duplicate declaration of position:absolute from [data-tooltip]:before

remove excess vendor prefixes from mixins, and recycle  transition mixin into fade mixin.

delete extra whitespace & convert sass only sections to sass comments so they don't compile in the unminified CSS.
Merge pull request #8 from scottaohara/develop

slight cleanup
Update demo.html
add silent classes, new customize output feature, other updates

reduced redundancy for [data-tooltip]:hover,:focus area

decreased selector specificity for .simptip-movable. Moved code into /** features **/ area

New silent classes to reduce class declarations in scss file.

convert diverse color hex values to variables and add them to variables section

Added new Customize CSS Output to turn on / off tooltip features and styling to reduce the amount of compiled CSS without having to actually delete any code.
Merge pull request #9 from scottaohara/silent_classes_and_new_feature

add silent classes, new customize output feature, other updates