Merge pull request #2806 from edx/frances/fix/lms-modal-button

making LMS modal buttons more flexible to handle longer strings in trans...

lms/static/sass/shared/_modal.scss

@@ -234,9 +234,10 @@
 
         input[type="submit"] {
           display: block;
-          height: 45px;
+          height: auto;
           margin: 0 auto;
           width: 100%;
+          white-space: normal;
         }
       }
     }