Update list-item-spacing message

Closes GH-60.
Closes GH-62.

Author: despairblue

lib/rules/list-item-spacing.js

@@ -103,10 +103,17 @@ function listItemSpacing(ast, file, preferred, done) {
              */
 
             if (isTight !== isTightList) {
-                file.warn('List item should be ' + type + ', isn’t', {
-                    'start': end(item),
-                    'end': start(next)
-                });
+                if (type === 'loose') {
+                    file.warn('Missing new line after list item', {
+                        'start': end(item),
+                        'end': start(next)
+                    });
+                } else {
+                    file.warn('Extraneous new line after list item', {
+                        'start': end(item),
+                        'end': start(next)
+                    });
+                }
             }
         });
     });

test/index.js

@@ -1416,13 +1416,13 @@ describe('Rules', function () {
     describeRule('list-item-spacing', function () {
         describeSetting(true, function () {
             assertFile('list-item-spacing-tight-invalid.md', [
-                 'list-item-spacing-tight-invalid.md:2:1-3:1: List item should be tight, isn’t',
-                 'list-item-spacing-tight-invalid.md:4:1-5:1: List item should be tight, isn’t'
+                 'list-item-spacing-tight-invalid.md:2:1-3:1: Extraneous new line after list item',
+                 'list-item-spacing-tight-invalid.md:4:1-5:1: Extraneous new line after list item'
             ]);
 
             assertFile('list-item-spacing-loose-invalid.md', [
-                 'list-item-spacing-loose-invalid.md:2:9-3:1: List item should be loose, isn’t',
-                 'list-item-spacing-loose-invalid.md:3:11-4:1: List item should be loose, isn’t'
+                 'list-item-spacing-loose-invalid.md:2:9-3:1: Missing new line after list item',
+                 'list-item-spacing-loose-invalid.md:3:11-4:1: Missing new line after list item'
             ]);
 
             assertFile('list-item-spacing-tight-valid.md', []);