Larger error message when submitting bad amount.

This addition to the Javascript and text ensures a clear message to the
user of a Javascript-enabled browser that there is an issue with the
amount.  Also, it prevents submission of the form until the amount is
correct.

A user with Javascript disabled can circumvent these validation steps;
however, the worst-case scenario is that they make a donation for less
than $120 that is categorized in Conservancy's internal system as a
Supporter donation, and we'll be adding internal checks to find that.

www/conservancy/static/supporter-page.js

@@ -43,12 +43,23 @@ $(document).ready(function() {
         if (isValid)  {
            input.removeClass("invalid").addClass("valid");
            errorElement.removeClass("form-error-show").addClass("form-error");
+           $("#form-correction-needed").removeClass("form-error-show").addClass("form-error");
         }
         else {
             input.removeClass("valid").addClass("invalid");
             errorElement.removeClass("form-error").addClass("form-error-show");
         }
     });
+    $("#supporter-form-submit").click(function(event){
+	var valid = $('#amount').hasClass("valid");
+        if (! valid) {
+            $("#form-correction-needed").removeClass("form-error").addClass("form-error-show")
+                                        .css("font-weight", "bold").css("font-size", "150%");
+	    event.preventDefault();
+        } else {
+            $("#form-correction-needed").removeClass("form-error-show").addClass("form-error");
+        }
+    });
     /* Handle toggling of annual/monthly form selections */
     $('.supporter-type-selection#monthly').hide();
     $('#annualSelector').css("font-weight", "bold").css("font-size", "127%");

www/conservancy/static/supporter/index.html

@@ -234,6 +234,7 @@ internal policies</a> are published and available for scrutiny.</p>
                       options to the right first.</small>
                       </div>
 </form>
+<span id="form-correction-needed" class="form-error">Please ensure all form data above is correct.</span>
 </div>
 </div>
 {% endblock %}