Initial commit for Jacket support.

Changes :
- Replaced `$mq-responsive` and `$mq-static-breakpoint` with Team Sass's Jacket; instead of outputting all styles from `$mq-static-breakpoint` and up, it will only output styles defined within `$mq-jacket-legacy` context. This allows various breakpoint ranges to be used.
- Added vertical management to accompany horizontal media queries; renamed `$mq-breakpoints` to `$mq-horizontal-breakpoints`.
- Moved core mixin operations to functions to allow query-chaining with the `$and` parameter.
- Added shortcut mixins and functions for rapid usage.
- Added doc-headings using Sass comments for readability.
- Updated README with some Jacket references.
- Updated Bower Configuration to include Jacket as a dependency.

Todo :
- Replace `str-replace` from Sassy Strings with Sass 3.3 Map functions.
- Add support for `$or`.
- Maybe : Remove Jacket as a dependency and provide fallback. I know, this sounds counter-intuitive to the whole concept of this variant.
Various minor changes relating to Sass 3.3 and Jacket.

Changes :
- Added `!global` for inheritance of deprecated `$mq-breakpoints` variable.
- Added deprecation warning for `$mq-breakpoints` variable.
- Set `!default` context for Jacket.
Removed dependency to "Team-Sass/Sassy-Strings".

Changes :
- Replaced `str-replace` mixin from "Team-Sass/Sassy-Strings" with basic Sass list functions, followed by implosion into a string.
Ignoring Bower.
Tests : Bare minimum update to test Jacket-support.