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

static/assets/bootstrap/sass/_dropdown.sass

@@ -0,0 +1,170 @@
+// The dropdown wrapper (`<div>`)
+.dropup,
+.dropright,
+.dropdown,
+.dropleft
+  position: relative
+
+.dropdown-toggle
+  // Generate the caret automatically
+  +caret
+
+// The dropdown menu
+.dropdown-menu
+  position: absolute
+  top: 100%
+  left: 0
+  z-index: $zindex-dropdown
+  display: none
+
+  // none by default, but block on "open" of the menu
+  float: left
+  min-width: $dropdown-min-width
+  padding: $dropdown-padding-y 0
+  margin: $dropdown-spacer 0 0
+
+  // override default ul
+  font-size: $font-size-base
+
+  // Redeclare because nesting can cause inheritance issues
+  color: $body-color
+  text-align: left
+
+  // Ensures proper alignment if parent has it changed (e.g., modal footer)
+  list-style: none
+  background-color: $dropdown-bg
+  background-clip: padding-box
+  border: $dropdown-border-width solid $dropdown-border-color
+
+  +border-radius($dropdown-border-radius)
+  +box-shadow($dropdown-box-shadow)
+
+.dropdown-menu-right
+  right: 0
+  left: auto
+
+// Allow for dropdowns to go bottom up (aka, dropup-menu)
+// Just add .dropup after the standard .dropdown class and you're set.
+.dropup
+  .dropdown-menu
+    top: auto
+    bottom: 100%
+    margin-top: 0
+    margin-bottom: $dropdown-spacer
+
+  .dropdown-toggle
+    +caret(up)
+
+.dropright
+  .dropdown-menu
+    top: 0
+    right: auto
+    left: 100%
+    margin-top: 0
+    margin-left: $dropdown-spacer
+
+  .dropdown-toggle
+    +caret(right)
+
+    &::after
+      vertical-align: 0
+
+.dropleft
+  .dropdown-menu
+    top: 0
+    right: 100%
+    left: auto
+    margin-top: 0
+    margin-right: $dropdown-spacer
+
+  .dropdown-toggle
+    +caret(left)
+
+    &::before
+      vertical-align: 0
+
+// When enabled Popper.js, reset basic dropdown position
+// stylelint-disable no-duplicate-selectors
+.dropdown-menu
+  &[x-placement^="top"],
+  &[x-placement^="right"],
+  &[x-placement^="bottom"],
+  &[x-placement^="left"]
+    right: auto
+    bottom: auto
+
+// stylelint-enable no-duplicate-selectors
+
+// Dividers (basically an `<hr>`) within the dropdown
+.dropdown-divider
+  +nav-divider($dropdown-divider-bg)
+
+// Links, buttons, and more within the dropdown menu
+//
+// `<button>`-specific styles are denoted with `// For <button>s`
+.dropdown-item
+  display: block
+  width: 100%
+
+  // For `<button>`s
+  padding: $dropdown-item-padding-y $dropdown-item-padding-x
+  clear: both
+  font-weight: $font-weight-normal
+  color: $dropdown-link-color
+  text-align: inherit
+
+  // For `<button>`s
+  white-space: nowrap
+
+  // prevent links from randomly breaking onto new lines
+  background-color: transparent
+
+  // For `<button>`s
+  border: 0
+
+  // For `<button>`s
+
+  +hover-focus
+    color: $dropdown-link-hover-color
+    text-decoration: none
+
+    +gradient-bg($dropdown-link-hover-bg)
+
+
+  &.active,
+  &:active
+    color: $dropdown-link-active-color
+    text-decoration: none
+
+    +gradient-bg($dropdown-link-active-bg)
+
+  &.disabled,
+  &:disabled
+    color: $dropdown-link-disabled-color
+    background-color: transparent
+
+    // Remove CSS gradients if they're enabled
+    @if $enable-gradients
+      background-image: none
+
+.dropdown-menu.show
+  display: block
+
+// Dropdown section headers
+.dropdown-header
+  display: block
+  padding: $dropdown-padding-y $dropdown-item-padding-x
+  margin-bottom: 0
+
+  // for use with heading elements
+  font-size: $font-size-sm
+  color: $dropdown-header-color
+  white-space: nowrap
+
+  // as with > li > a
+
+// Dropdown text
+.dropdown-item-text
+  display: block
+  padding: $dropdown-item-padding-y $dropdown-item-padding-x
+  color: $dropdown-link-color