Remove extra ( " ) on Draw plugin template (#1120)

Fixed JS "SyntaxError.." produced by an extra (") on Draw plugin template.

Author: fullonic

folium/plugins/__init__.py

@@ -59,4 +59,4 @@
     'TimeSliderChoropleth',
     'TimestampedGeoJson',
     'TimestampedWmsTileLayers',
-    ]
+]

folium/plugins/draw.py

@@ -76,7 +76,7 @@ class Draw(MacroElement):
                     'href', 'data:' + convertedData
                 );
                 document.getElementById('export').setAttribute(
-                    'download', {{ this.filename|tojson }}"
+                    'download', {{ this.filename|tojson }}
                 );
             }
         {% endmacro %}