Use tea-error
Removed useless comment
Added flatPermissionTree tests
Removed _simplePermissions tests, updated addPermissions tests
Added argument testing to addPermission function
Removed now useless _simplePermissions function
Updated documentation
Refactored simplePermissions into flatPermissionTree
Added protect tests
Added argument testing to lookupPermissions
Fixed typo in tests
Added argument checking to _protect
Removed useless comment
Added argument checking to exported function
Changed protect to _protect to relfect its prvacy