Remove national flags from the language select.(Solution 2) (#825)

* Remove national flags from the language select.

* Removed flag-icon-css.

* Removed the line break for old language select.

assets/img/flags/4x3/nl.svg

@@ -1,7 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" height="480" width="640" version="1">
-  <g fill-rule="evenodd" stroke-width="1pt" transform="scale(1.25 .9375)">
-    <rect rx="0" ry="0" height="509.76" width="512" fill="#fff"/>
-    <rect rx="0" ry="0" height="169.92" width="512" y="342.08" fill="#21468b"/>
-    <path fill="#ae1c28" d="M0 0h512v169.92H0z"/>
-  </g>
-</svg>