Implement custom blocks to be inserted in nginx config.

This is a go at #97 
Fixing this involves a lot more then just wrapping the line. 

Proper fix would be to either introduce some helper modules and call methods such as `certificate_exists_for?(app)`. 

The next best thing, and more chef-ish, is to make these blocks into LWRPs. That allows for a lot of cleaning up.

The next best thing is to extract all these into variables, but that really does not make the code more readable.

Alll this is is a much larger, and different task than what I'm trying to achieve in this PR,