Update help documentation
Finish implementing signature checking
Change config format to yaml

Yaml is a better solution for config files than JSON. It is easier to write,
and easier to read. The only downside is that it is not in the standard
library.
Fix signature check argument

Missed a bool check causing the signatures to be generated when using the
--no-check argument.
Add pprint debug output in package.py
Stop installing the packages with the build command

Instead fallback to the dependency checker to install the package when needed.