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

static/assets/bootstrap/sass/_list-group.sass

@@ -0,0 +1,109 @@
+// Base class
+//
+// Easily usable on <ul>, <ol>, or <div>.
+
+.list-group
+  display: flex
+  flex-direction: column
+
+  // No need to set list-style: none; since .list-group-item is block level
+  padding-left: 0
+
+  // reset padding because ul and ol
+  margin-bottom: 0
+
+// Interactive list items
+//
+// Use anchor or button elements instead of `li`s or `div`s to create interactive
+// list items. Includes an extra `.active` modifier class for selected items.
+
+.list-group-item-action
+  width: 100%
+
+  // For `<button>`s (anchors become 100% by default though)
+  color: $list-group-action-color
+  text-align: inherit
+
+  // For `<button>`s (anchors inherit)
+
+  // Hover state
+  +hover-focus
+    color: $list-group-action-hover-color
+    text-decoration: none
+    background-color: $list-group-hover-bg
+
+
+  &:active
+    color: $list-group-action-active-color
+    background-color: $list-group-action-active-bg
+
+// Individual list items
+//
+// Use on `li`s or `div`s within the `.list-group` parent.
+
+.list-group-item
+  position: relative
+  display: block
+  padding: $list-group-item-padding-y $list-group-item-padding-x
+
+  // Place the border on the list items and negative margin up for better styling
+  margin-bottom: -$list-group-border-width
+  background-color: $list-group-bg
+  border: $list-group-border-width solid $list-group-border-color
+
+  &:first-child
+    +border-top-radius($list-group-border-radius)
+
+  &:last-child
+    margin-bottom: 0
+
+    +border-bottom-radius($list-group-border-radius)
+
+  +hover-focus
+    z-index: 1
+
+    // Place hover/active items above their siblings for proper border styling
+    text-decoration: none
+
+
+  &.disabled,
+  &:disabled
+    color: $list-group-disabled-color
+    background-color: $list-group-disabled-bg
+
+  // Include both here for `<a>`s and `<button>`s
+  &.active
+    z-index: 2
+
+    // Place active items above their siblings for proper border styling
+    color: $list-group-active-color
+    background-color: $list-group-active-bg
+    border-color: $list-group-active-border-color
+
+// Flush list items
+//
+// Remove borders and border-radius to keep list group items edge-to-edge. Most
+// useful within other components (e.g., cards).
+
+.list-group-flush
+  .list-group-item
+    border-right: 0
+    border-left: 0
+
+    +border-radius(0)
+
+  &:first-child
+    .list-group-item:first-child
+      border-top: 0
+
+  &:last-child
+    .list-group-item:last-child
+      border-bottom: 0
+
+// Contextual variants
+//
+// Add modifier classes to change text and background color on individual items.
+// Organizationally, this must come after the `:hover` states.
+
+@each $color, $value in $theme-colors
+  +list-group-item-variant($color, theme-color-level($color, -9), theme-color-level($color, 6))