Fix problem with local search when site_url is not at the root

When the site url is not at the root, the localsearch plugin __init__.py needed to be modified slightly to include the folder when using the post permalink. In addition, I added some corresponding comments to the conf.py.sample.
Another better way that is automated would be to do string concatenation with the full site URL — provided Tipue can do full paths in contentLocation.

Also, On another thought, the HTML tags should be handled automatically by Nikola and you needn’t intervene with them.