Install a sample www directory

[yoneken]

To use a sample www directory, it should be installed under the share directory.

When I launched roswww with the default webpath param (www), http://localhost:8085/roswww/ points _~/yoneken/ros/installisolated/share/roswww/www/index.html.

[130s]

roswww/www folder contains nothing important, nor it's utilized by the default launch file roswww.launch either (I created a test to ensure this). But exporting the www folder doesn't do any harm, so +1.