Fix #2758: Uneditable inputs in input-prepend/append

1. Added a missing comma to the input-append's form control stack () to fix border-radius
2. Add  to the .uneditable-input in forms to remove the float as we do with all other form controls

less/forms.less

@@ -243,7 +243,7 @@ select:focus {
 input[class*="span"],
 select[class*="span"],
 textarea[class*="span"],
-.uneditable-input {
+.uneditable-input[class*="span"] {
   float: none;
   margin-left: 0;
 }
@@ -408,7 +408,7 @@ select:focus:required:invalid {
 }
 .input-append {
   input,
-  select
+  select,
   .uneditable-input {
     .border-radius(3px 0 0 3px);
   }