Switch roles to get different permissions

[craigchandler]

I'm submitting a...

[ ] Regression (a behavior that used to work and stopped working in a new release)
[ ] Bug report  
[ ] Feature request
[X ] Documentation issue or request

Current behavior

Currently to change a user's roles I'm flushing all roles and permissions then rebuilding all roles permissions that apply, this doesn't seem the best way.

Expected behavior

Can I add a set of roles with permissions then change which roles the current user has or should I look to a different library?
I cant seem to even delete 1 role as its permissions get left behind