refactor(css): dropping most -moz- css prefixes

Most `-moz-` css prefixes are no longer required as of Firefox 16:
http://paulrouget.com/e/unprefixing-in-firefox-16/

scss/_mixins.scss

@@ -172,7 +172,7 @@
 // --------------------------------------------------
 
 @mixin placeholder($color: $input-color-placeholder, $text-indent: 0) {
-  &::-moz-placeholder { /* Firefox 19+ */
+  &::-moz-placeholder { // Firefox 19+
     color: $color;
   }
   &:-ms-input-placeholder {
@@ -253,29 +253,24 @@
 
 @mixin border-radius($radius) {
   -webkit-border-radius: $radius;
-     -moz-border-radius: $radius;
           border-radius: $radius;
 }
 
 // Single Corner Border Radius
 @mixin border-top-left-radius($radius) {
   -webkit-border-top-left-radius: $radius;
-      -moz-border-radius-topleft: $radius;
           border-top-left-radius: $radius;
 }
 @mixin border-top-right-radius($radius) {
   -webkit-border-top-right-radius: $radius;
-      -moz-border-radius-topright: $radius;
           border-top-right-radius: $radius;
 }
 @mixin border-bottom-right-radius($radius) {
   -webkit-border-bottom-right-radius: $radius;
-      -moz-border-radius-bottomright: $radius;
           border-bottom-right-radius: $radius;
 }
 @mixin border-bottom-left-radius($radius) {
   -webkit-border-bottom-left-radius: $radius;
-      -moz-border-radius-bottomleft: $radius;
           border-bottom-left-radius: $radius;
 }
 
@@ -303,7 +298,6 @@
 
 @mixin box-shadow($shadow...) {
   -webkit-box-shadow: $shadow;
-     -moz-box-shadow: $shadow;
           box-shadow: $shadow;
 }
 
@@ -313,33 +307,27 @@
 
 @mixin transition($transition...) {
   -webkit-transition: $transition;
-     -moz-transition: $transition;
           transition: $transition;
 }
 @mixin transition-delay($transition-delay) {
   -webkit-transition-delay: $transition-delay;
-     -moz-transition-delay: $transition-delay;
           transition-delay: $transition-delay;
 }
 @mixin transition-duration($transition-duration) {
   -webkit-transition-duration: $transition-duration;
-     -moz-transition-duration: $transition-duration;
           transition-duration: $transition-duration;
 }
 @mixin transition-timing-function($transition-timing) {
    -webkit-transition-timing-function: $transition-timing;
-      -moz-transition-timing-function: $transition-timing;
            transition-timing-function: $transition-timing;
  }
  @mixin transition-property($property) {
   -webkit-transition-property: $property;
-     -moz-transition-property: $property;
           transition-property: $property;
 }
 @mixin transition-transform($properties...) {
   // special case cuz of transform vendor prefixes
   -webkit-transition: -webkit-transform $properties;
-     -moz-transition: -moz-transform $properties;
           transition: transform $properties;
 }
 
@@ -349,37 +337,30 @@
 
 @mixin animation($animation) {
  -webkit-animation: $animation;
-    -moz-animation: $animation;
          animation: $animation;
 }
 @mixin animation-duration($duration) {
  -webkit-animation-duration: $duration;
-    -moz-animation-duration: $duration;
          animation-duration: $duration;
 }
 @mixin animation-direction($direction) {
  -webkit-animation-direction: $direction;
-    -moz-animation-direction: $direction;
          animation-direction: $direction;
 }
 @mixin animation-timing-function($animation-timing) {
  -webkit-animation-timing-function: $animation-timing;
-    -moz-animation-timing-function: $animation-timing;
          animation-timing-function: $animation-timing;
 }
 @mixin animation-fill-mode($fill-mode) {
  -webkit-animation-fill-mode: $fill-mode;
-    -moz-animation-fill-mode: $fill-mode;
          animation-fill-mode: $fill-mode;
 }
 @mixin animation-name($name...) {
  -webkit-animation-name: $name;
-    -moz-animation-name: $name;
          animation-name: $name;
 }
 @mixin animation-iteration-count($count) {
  -webkit-animation-iteration-count: $count;
-    -moz-animation-iteration-count: $count;
          animation-iteration-count: $count;
 }
 
@@ -408,13 +389,11 @@
 }
 @mixin transform($val) {
   -webkit-transform: $val;
-     -moz-transform: $val;
           transform: $val;
 }
 
 @mixin transform-origin($left, $top) {
   -webkit-transform-origin: $left $top;
-     -moz-transform-origin: $left $top;
           transform-origin: $left $top;
 }
 
@@ -435,7 +414,6 @@
 
 @mixin background-clip($clip) {
   -webkit-background-clip: $clip;
-     -moz-background-clip: $clip;
           background-clip: $clip;
 }
 
@@ -445,7 +423,6 @@
 
 @mixin background-size($size) {
   -webkit-background-size: $size;
-     -moz-background-size: $size;
           background-size: $size;
 }