enable font awesome in form controls

the form controls are preconfigured to use glyhicons but lack the support for FA icons

build/less/forms.less

@@ -79,4 +79,20 @@
 
 .icheck > label {
   padding-left: 0;
-}
+}
+
+/* support Font Awesome icons in form-control */
+.form-control-feedback.fa {
+    line-height: @input-height-base;
+}
+
+.input-lg + .form-control-feedback.fa,
+.input-group-lg + .form-control-feedback.fa,
+.form-group-lg .form-control + .form-control-feedback.fa {
+  line-height: @input-height-large;
+}
+.input-sm + .form-control-feedback.fa,
+.input-group-sm + .form-control-feedback.fa,
+.form-group-sm .form-control + .form-control-feedback.fa {
+  line-height: @input-height-small;
+}