Add a way to document permissions in the API

[allmightyspiff]

• add a @SLDNDocumentation Permission <PERMISSION_KEY> documentation tag
• Add that to the generator
• Update the codebase for methods that do permission checks

[allmightyspiff]

Also Fix error handling see https://sldn.softlayer.com/reference/services/SoftLayer_Account/setVlanSpan/