* fix: swithc WhitelistedCrowdsale to use Whitelist.sol

* feat: refactor whitelist.sol, rbac.sol and whitelistedcrowdsale.sol

* feat: add event arg assets and update whitelist

* fix: update modifier comment and also test isWhitelisted

* fix: remove onlyWhitelisted backwards compat attempt, fix explicit inheritance

* fix: remove underscore prefix from event args

* fix: user access/Whitelist