Adding a function to convert keywords use in search to SEO friendly urls fixes #66

This pull request fixes #66.

A new function has been added to modify the search keyword to a more SEO friendly url:

![image](https://cloud.githubusercontent.com/assets/3870763/2836978/3a6e8a48-d00b-11e3-90c1-17d2a8ee7434.png)

![image](https://cloud.githubusercontent.com/assets/3870763/2836984/4529f59e-d00b-11e3-8212-4030a93224ea.png)

This feature also fixes various keywords:
``becha_by_golly_wow``       : ``shop/becha-by-golly-wow``
``b3ch@ by G**lly WOW!!!!`` : ``shop/b3ch-by-glly-wow``

@deanearlbartolabac I have added the clean up under ``is_search`` structure is ``%postname%`` kindly check if there are more code blocks where the keyword needs to be converted to this. Thanks