Consistency within R package and with REST API

[nickdickinson]

Rest API and function arguments are sometimes inconsistent or redundant. This issue can be used to track these

List:

• [ ] roleAssignment() used in updateUserRole() but not in addDatabaseUser(). Use both or neither in next major version change.
• [ ] roleAssignment() has arguments roleParameter= and roleResources= but would better match API by having parameter= and resources= arguments.