Fixed pagination link error when <DIRECT_TEMPLATE_NAME>_SAVE_AS setting used.

The unit test for this scenario was passing as it was testing for an incorrect 'page_name' variable being set.
delete output directory properly
Settings file is pelicanconf.py now.
added unique filtering and config limit param

I hacked some code from other modules and some quick googling, first time with py so this may need to be cleaned up.

The functionality is to have a config var in pythonconfig.py and to remove the duplicates `sorted(set())`
Relative URL issues with the related post examples

I noted that if you set the `ARTICLE_URL` site variable to have some depth and just create relative links, they will not link correctly.

by prefacing the link with `{{ SITEURL}}/` it seems to ensure proper links are created and works with the `make devserver` mode