Support for custom installation folder and rc.local backup

Hi, I thought these changes would be helpful, since they have been at least for me.
Some people, like me, could have a custom rc.local file, and it would get overwritten upon install otherwise.
I also added the support for custom install directory, which defaults to the webserver root folder.
Furthermore, the apache virtual host configuration file is generated automatically by the installer itself, taking in account the custom folder the user could possibly customise.
I realise there may be a more efficient way to do so, but at the moment for my needs it did the job.