Fix deprecation warnings from Dart Sass (#801)

Merge pull request 801

Author: ashmaroli

_sass/minima/_base.scss

@@ -37,7 +37,7 @@ h1, h2, h3, h4, h5, h6,
 p, blockquote, pre,
 ul, ol, dl, figure,
 %vertical-rhythm {
-  margin-bottom: $spacing-unit / 2;
+  margin-bottom: $spacing-unit * 0.5;
 }
 
 
@@ -131,7 +131,7 @@ a {
 blockquote {
   color: $grey-color;
   border-left: 4px solid $grey-color-light;
-  padding-left: $spacing-unit / 2;
+  padding-left: $spacing-unit * 0.5;
   @include relative-font-size(1.125);
   letter-spacing: -1px;
   font-style: italic;
@@ -186,8 +186,8 @@ pre {
   @include media-query($on-laptop) {
     max-width: -webkit-calc(#{$content-width} - (#{$spacing-unit}));
     max-width:         calc(#{$content-width} - (#{$spacing-unit}));
-    padding-right: $spacing-unit / 2;
-    padding-left: $spacing-unit / 2;
+    padding-right: $spacing-unit * 0.5;
+    padding-left: $spacing-unit * 0.5;
   }
 }
 
@@ -241,7 +241,7 @@ table {
     }
   }
   th, td {
-    padding: ($spacing-unit / 3) ($spacing-unit / 2);
+    padding: ($spacing-unit * 0.3333333333) ($spacing-unit * 0.5);
   }
   th {
     background-color: lighten($grey-color-light, 3%);

_sass/minima/_layout.scss

@@ -49,7 +49,7 @@
   @include media-query($on-palm) {
     position: absolute;
     top: 9px;
-    right: $spacing-unit / 2;
+    right: $spacing-unit * 0.5;
     background-color: $background-color;
     border: 1px solid $grey-color-light;
     border-radius: 5px;
@@ -90,12 +90,12 @@
 
     .page-link {
       display: block;
+      margin-left: 20px;
       padding: 5px 10px;
 
       &:not(:last-child) {
         margin-right: 0;
       }
-      margin-left: 20px;
     }
   }
 }
@@ -112,7 +112,7 @@
 
 .footer-heading {
   @include relative-font-size(1.125);
-  margin-bottom: $spacing-unit / 2;
+  margin-bottom: $spacing-unit * 0.5;
 }
 
 .contact-list,
@@ -124,14 +124,14 @@
 .footer-col-wrapper {
   @include relative-font-size(0.9375);
   color: $grey-color;
-  margin-left: -$spacing-unit / 2;
+  margin-left: -$spacing-unit * 0.5;
   @extend %clearfix;
 }
 
 .footer-col {
   float: left;
-  margin-bottom: $spacing-unit / 2;
-  padding-left: $spacing-unit / 2;
+  margin-bottom: $spacing-unit * 0.5;
+  padding-left: $spacing-unit * 0.5;
 }
 
 .footer-col-1 {