Migrating policy methods out of the repository

I want a proper policy layer to be applied
Adding Policies.with_authorization_enforcement
Adding Sipity::PolicyEnforcer
Adding authorization enforcement layer

Teasing apart the authorization layer
Applying authorization layer to runners
Merge pull request #22 from ndlib/extracting-policies

Extracting policies
Improving documentation

[skip ci]
Tidying up runner behavior
Tidying up rspec documentation

[skip ci]