Easy installation on cloudControl

Prepared Tiny-Tiny-RSS to be easily deployable on cloudControl (http://www.cloudcontrol.com).

Changes:
 - ttrssmailer.php: The current implementation didn't seem to work with smtp - fixed.
 - README.md: Extended with simple steps how to set it up.
 - Procfile: The file is used to define how the the application should be started and how to run a worker / updater.
 - config.php: Here are the main changes. The database and mail settings are automatical taken from the environment. I decided to use the config.php instead of a seperate file (config.php-cloudControl) to provide the possibility to clone the code, push it to cloudControl and you are done.

I know this are more or less specific changes, but I think still makes sense. This could enable more people to try out Tiny-Tiny-RSS without the need of having and maintaining their own servers.
The main changes don't interfer with anything else. The Procfile can just be ignored and is also used by other PaaS providers. The config.php file is normaly overwritten with the config.php-dist, so it shouldn't make a difference.
 
Hint: I'm working for cloudControl