Fix escaping of single quote. Closes #307, updates tests.

lib/carto/tree/quoted.js

@@ -10,7 +10,7 @@ tree.Quoted.prototype = {
     toString: function(quotes) {
         var xmlvalue = this.value
             .replace(/&/g, '&')
-            .replace(/\'/g, ''')
+            .replace(/\'/g, '\\\'')
             .replace(/\"/g, '"')
             .replace(/</g, '&lt;')
             .replace(/\>/g, '&gt;');

test/quoted.test.js

@@ -17,7 +17,7 @@ describe('Quoted', function() {
         it('should produce xml-friendly output', function() {
             var f = new tree.Quoted("Tom's & \"<quoted>\"");
             assert.ok(f);
-            assert.equal(f.toString(true), "'Tom&apos;s &amp; &quot;&lt;quoted&gt;&quot;'");
+            assert.equal(f.toString(true), "'Tom\\'s &amp; &quot;&lt;quoted&gt;&quot;'");
         });
     });
 });

test/rendering/filterquote.result

@@ -5,7 +5,7 @@
 
 <Style name="world" filter-mode="first">
   <Rule>
-    <Filter>([name2] = ' Sa&apos;ad')</Filter>
+    <Filter>([name2] = ' Sa\'ad')</Filter>
     <PolygonSymbolizer fill="#ffffff" />
   </Rule>
 </Style>