feature: allow for multiple config files

[0ff]

Hey there, thanks for your awesome work!
This really gave me a great starting point so I wanted to let you know I've extended your tool to allow for multiple config files.

As confd does not support this out-of-the-box, I've implemented it by using awk and splitting a config-template that's actually made up of multiple templates.
You can see my changes here, maybe if you like we could develop a merged version that supports both single and multiple files (so that existing installations won't break).