Add responsiveness for footer. Update gulpjs, package.json and bootstrap sass

static/assets/bootstrap/sass/utilities/_spacing.sass

@@ -0,0 +1,48 @@
+// stylelint-disable declaration-no-important
+
+// Margin and Padding
+
+@each $breakpoint in map-keys($grid-breakpoints)
+  +media-breakpoint-up($breakpoint)
+    $infix: breakpoint-infix($breakpoint, $grid-breakpoints)
+
+    @each $prop, $abbrev in (margin: m, padding: p)
+      @each $size, $length in $spacers
+        .#{$abbrev}#{$infix}-#{$size}
+          #{$prop}: $length !important
+
+        .#{$abbrev}t#{$infix}-#{$size},
+        .#{$abbrev}y#{$infix}-#{$size}
+          #{$prop}-top: $length !important
+
+        .#{$abbrev}r#{$infix}-#{$size},
+        .#{$abbrev}x#{$infix}-#{$size}
+          #{$prop}-right: $length !important
+
+        .#{$abbrev}b#{$infix}-#{$size},
+        .#{$abbrev}y#{$infix}-#{$size}
+          #{$prop}-bottom: $length !important
+
+        .#{$abbrev}l#{$infix}-#{$size},
+        .#{$abbrev}x#{$infix}-#{$size}
+          #{$prop}-left: $length !important
+
+    // Some special margin utils
+    .m#{$infix}-auto
+      margin: auto !important
+
+    .mt#{$infix}-auto,
+    .my#{$infix}-auto
+      margin-top: auto !important
+
+    .mr#{$infix}-auto,
+    .mx#{$infix}-auto
+      margin-right: auto !important
+
+    .mb#{$infix}-auto,
+    .my#{$infix}-auto
+      margin-bottom: auto !important
+
+    .ml#{$infix}-auto,
+    .mx#{$infix}-auto
+      margin-left: auto !important