System / Site roles refactor

SystemRoles created with roles "system_admin", "user", "none"
SiteRoles has roles "site_manager", "project_creator", "user"
project_creator is a user that has permissions to create projects on a site

Previous references to Site Admin converted to System Admin

UserModelBase has role (system) and siteRole
TODO: populate siteRole

Test environment setups updated to populate projectCodes when creating test projects