This commit adds repository_gpgcheck and package_gpgcheck attributes
to the repository tag in schema. With this change each repository
can be configured individualy to enable repository signatures check
and/or enable signature package check. The configuration is done at
repository level, thus it is not conflicting with the wide package
manager configuration flag <rpm-signatures-check>.
Fixes#358
The current design of the documentation does not allow for
continous improvement and development. It's missing a basic
structure and concept for documenting step-by-step workflows
and generic explanations.
