Reorganised the script adding a PornTrexBaseIE class that will be used
for shared methods. Currently hosting only two methods:
1. _login
2. _real_initialize
Added login and password to playlist class.
Also added a new playlist for the the test of the playlist class.
I do not know how to test the credentials in youtube-dl yet so needed a class that did not need username and password and that had all its videos available for access.
