Bug fixes, cleanup.
- Fixed FontAwesome path. Removed slash (fa-font-path already has a slash)
- Changed %document to use @include instead of @extend (placeholders defined in layout, an optional module). Placeholders might need to be moved to mixins.
- Fixed(?) tests. Loaded layout module in each, since they appeared to test layouts and make use of layout placeholders.
- Removed "responsive" directory. Doesn't appear to affect everything in 3.0 and will be unnecessary after these changes.
New features.
- Added respond-min and respond-max media query mixins, based on this ()
- Added breakpoint loop mixin, suited for mobile-first loops where each iteration overrides the last. Compares each breakpoint to a “default” to determine if a breakpoint target should be supplied.
  - Takes two parameters:
    - $base: The base which shouldn't have a "target" (.one-half-small-tablet has the target "-small-tablet" appended to it)
    - $separator: Character used to prepend/append target (defaults to "-")
  - Provides six helper vars to loop:
    - $bp: Name of the current breakpoint, as defined in settings
    - $bp-index: One-based index of the current breakpoint
    - $bp-target: Suggested target for scoping classes ('' on default-base)
    - $bp-target-pre: Suggested target as prefix ('target-', '' on default-base)
    - $bp-target-post: Suggested target as postfix ('-target', '' on default-base)
    - $bp-target-mid: Suggested target as term ('-target-', '' on default-base)
- Added settings defining breakpoints across the framework:
  - $breakpoints: Breakpoint identifiers to use in class/placeholder names
  - $breakpoint-sizes: Minimum widths for each breakpoint in $breakpoints (respectively)
  - $default-base: Breakpoint that shouldn't have a target ("desktop" means ".one-half-desktop" becomes ".one-half")
  - $fixed-size: Size that media queries should emulate (Useful for IE8 fallback)
Refactored grid.
- Replaced _grid.scss logic with a couple breakpoints loops
- Moved adapter block mixin to mixin “grid-adapters” under “grid-selectors”
- Moved $grid-selector-types from global space to parameter of “grid-selectors” mixin (Also added)
- Rewrote “columns” and “blocks” mixins to take a list (mirroring $breakpoints definition format) and use a breakpoints loop
- Added extra check for empty $target. Sass seems to treat bools as string (false == "false") in concatenation.
- Added internal-only placeholders to collect common rules per each media query.
- Modified tests to fit new syntax (mobile widths first).
- Added $grid-base setting for defining default-base for grid selectors (defaults to $default-base)

Note: collapse-on-* was not reimplemented, though mixin was kept.
Refactored helpers.
- Replaced _helpers.scss logic with one breakpoint loop.
- Removed previous breakpoint helper mixins (responsive_*).
- Added "no-border" to definable list of $border-helpers
Refactored navigation.
- Rewrote to be mobile first (start off as hamburger)
- Replaced “hamburger-mode” mixin with “bar-mode” mixin
- Added "bar" selector to navs that specify point at which navigation becomes a dropdown/bar.
- Added $navigation-base setting for defining default-base for navigation selectors (defaults to $default-base)
Refactored html.
- Changed docs to use new mobile-first syntax.
- Removed reference to “breakpoints.scss”, since breakpoints are defined in settings already
Merge pull request #239 from JProffitt71/3.0.0-wip-mobile-first

3.0.0 wip mobile first