use findorCreate to create roles

[ningsuhen]

The Role creation helper creates a new/duplicate role everytime even if it is of the same name. However, this is not very helpful. Role names should be unique. Also, in a system where there are pre-created roles like 'admin', I think that findOrCreate works better. Please merge this if you think this is a legit argument.

[slnode]

Can one of the admins verify this patch? To accept patch and trigger a build add comment ".ok\W+to\W+test."

[bajtos]

@slnode ok to test

[ritch]

Thanks @ningsuhen