Provide .less style for bootstrap-tagsinput

We use flatly theme for bootstrap while bootstrap-tagsinput bundles a css file that follow vanilla style, create a less version and use it instead of the css one bundles with bootstrap-tagsinput.
typeahead.js allows to customize class names used for UI elements, but bootstrap-tagsinput doesn't support passing that and is no longer maintained, so we need to follow default typeahead.js classes.

assets/static/base.css

@@ -353,17 +353,6 @@ button.silence-delete:focus {
     background-color: #e74c3c;
 }
 
-/* tweak typeahead look for flatly */
-.tt-cursor,
-.tt-suggestion:hover,
-.tt-suggestion:focus {
-    color: #ffffff;
-    text-decoration: none;
-    outline: 0;
-    background-color: #2c3e50;
-}
-
-
 /* tweak nprogress look for flatly */
 #nprogress .nprogress-flatly.bar {
     background: #f39c12;

assets/static/bootstrap-tagsinput.less

@@ -0,0 +1,53 @@
+// lessified version of https://github.com/bootstrap-tagsinput/bootstrap-tagsinput/blob/master/src/bootstrap-tagsinput-typeahead.css
+
+@import "bootstrap/less/variables.less";
+
+.twitter-typeahead .tt-query,
+.twitter-typeahead .tt-hint {
+    margin-bottom: 0;
+}
+
+.twitter-typeahead .tt-hint {
+    display: none;
+}
+
+.tt-menu {
+    position: absolute;
+    top: 100%;
+    left: 0;
+    z-index: @zindex-dropdown;
+    display: none;
+    float: left;
+    min-width: 160px;
+    padding: 5px 0;
+    margin: 2px 0 0;
+    list-style: none;
+    font-size: @font-size-base;
+    background-color: @dropdown-bg;
+    border: 1px solid @dropdown-fallback-border;
+    border: 1px solid @dropdown-border;
+    border-radius: @border-radius-base;
+    -webkit-box-shadow: 0 6px 12px rgba(0, 0, 0, 0.175);
+    box-shadow: 0 6px 12px rgba(0, 0, 0, 0.175);
+    background-clip: padding-box;
+    cursor: pointer;
+}
+
+.tt-suggestion {
+    display: block;
+    padding: 3px 20px;
+    clear: both;
+    font-weight: normal;
+    line-height: @line-height-base;
+    color: @dropdown-link-color;
+    white-space: nowrap;
+}
+
+.tt-cursor,
+.tt-suggestion:hover,
+.tt-suggestion:focus {
+    color: @dropdown-link-hover-color;
+    text-decoration: none;
+    outline: 0;
+    background-color: @dropdown-link-hover-bg;
+}

assets/static/filters.js

@@ -8,7 +8,7 @@ require("./jquery.typing-0.3.2.js");
 require("corejs-typeahead");
 require("bootstrap-tagsinput");
 require("bootstrap-tagsinput/dist/bootstrap-tagsinput.css");
-require("bootstrap-tagsinput/dist/bootstrap-tagsinput-typeahead.css");
+require("./bootstrap-tagsinput.less");
 
 const autocomplete = require("./autocomplete");
 const unsee = require("./unsee");