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

static/assets/bootstrap/sass/mixins/_grid-framework.sass

@@ -0,0 +1,62 @@
+// Framework grid generation
+//
+// Used only by Bootstrap to generate the correct number of grid classes given
+// any value of `$grid-columns`.
+
+=make-grid-columns($columns: $grid-columns, $gutter: $grid-gutter-width, $breakpoints: $grid-breakpoints)
+  // Common properties for all breakpoints
+  %grid-column
+    position: relative
+    width: 100%
+    min-height: 1px
+
+    // Prevent columns from collapsing when empty
+    padding-right: $gutter / 2
+    padding-left: $gutter / 2
+
+  @each $breakpoint in map-keys($breakpoints)
+    $infix: breakpoint-infix($breakpoint, $breakpoints)
+
+    // Allow columns to stretch full width below their breakpoints
+    @for $i from 1 through $columns
+      .col#{$infix}-#{$i}
+        @extend %grid-column
+
+    .col#{$infix},
+    .col#{$infix}-auto
+      @extend %grid-column
+
+    +media-breakpoint-up($breakpoint, $breakpoints)
+      // Provide basic `.col-{bp}` classes for equal-width flexbox columns
+      .col#{$infix}
+        flex-basis: 0
+        flex-grow: 1
+        max-width: 100%
+
+      .col#{$infix}-auto
+        flex: 0 0 auto
+        width: auto
+        max-width: none
+
+        // Reset earlier grid tiers
+
+      @for $i from 1 through $columns
+        .col#{$infix}-#{$i}
+          +make-col($i, $columns)
+
+      .order#{$infix}-first
+        order: -1
+
+      .order#{$infix}-last
+        order: $columns + 1
+
+      @for $i from 0 through $columns
+        .order#{$infix}-#{$i}
+          order: $i
+
+      // `$columns - 1` because offsetting by the width of an entire row isn't possible
+      @for $i from 0 through $columns - 1
+        @if not ($infix == "" and $i == 0)
+          // Avoid emitting useless .offset-0
+          .offset#{$infix}-#{$i}
+            +make-col-offset($i, $columns)