Adding functionality to redirect to the setup path

I'm adding the functionality needed to be able to redirect to the setup
path (in this case, install.php). This change is required to ensure that
the user doesn't forget to install the CMS before trying to utilize it.
Updating install.php with better subdirectory detection

The dirname($_SERVER['PHP_SELF']) enables us to detect the current subdirectory
where the the CMS is installed.

Example:

Installed in localhost/ejanuszewski-cms/
Modified code returns: /ejanuszewski-cms
Previous code returned: localhost
Updated missing config variable
Removing the classes/config.class.php file from repo

I'm removing the classes/config.class.php file from the repo as it should
probably not be "tracked" so to speak. Any necessary changes should be made
in the classes/config.class.sample.php, and installation specific changes
can be made in the other one.

By removing it from the repo, we can set up our local copies without risking
the passwords being pushed out on the internet. After all, we won't be changing
those values in the configuration anytime soon.
Updating unexpected copy&paste
Technically not working too good if you try to use a method from a non-existent class
Merge pull request #2 from ninetwozero/fixing-setup-procedure

Fixing setup procedure