[Owncloud] Change username of owncloud users

[Bert Haverkamp]

Dear all,

First of all, happy newyear! Thank you for this great project! I hope 
2014 will bring a lot of new features.
One question. Is there an easy way to change the username of an owncloud 
user?
I started using int for my family and used just first names. But I want 
to move away from this to use email address formats, as both me and my 
wife have a private and work account and I have enabled roundcube within 
owncould. So Bert should become Bert at mydomain.nl, etc.
Is it a matter of a single table to edit in the database and renaming 
the data directories, or is there more to it?

Kind regards,

Bert