Add whitespace between short description, long description, and parameters.
Prefix helper function names to avoid collisions.
Extract duplicated code to create Nginx logs into helper function.
Extract duplicated code to import MySQL database into helper function.
Use a variable for the site domain instead of hardcoding it in multiple places.
Clarify where the sites will be created.

Since VVV also stores the provision scripts in `www`, people might be confused.
Add more TODOs.