Added Additional Error Handling in Email Previews, Restructured the VirtualHost Files

Originally PF would store all of the phishing sites in one single Apache file `/etc/apache2/httpd.conf`. This is a flawed design because if the syntax is off on one single phishing site it will mess up all of the active phishing campaigns as well.

This PR will manage the VirtualHosts by placing a single file for each active campaign located in `/etc/apache2/sites-enabled` by default.

Additionally this PR adds a number of Error Handling features within the Email Preview, Launch and Test. This Error Handling has also been improved on the Site Cloner.

@mcjon3z  and @altjx any chance I can get a QA review on this development branch?  I'd like to hear your guys' feedback before merging this into master.