Fix select2 css for drop above style

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/assets/stylesheets/generic/selects.scss

 /** Select2 selectbox style override **/
-.select2-container {
+.select2-container, .select2-container.select2-drop-above {
   .select2-choice {
     background: #FFF;
     border-color: #BBB;