When setting up LDAP authentication, an uncaught exception may be thrown

when splitting the full name into first name and last name. This happens

when the full name contains no space.
If this exception occurs it will now assign the full name to the first

name, and make the last name an empty string.

Because there was a comment just above my changes explaining how full

name is split between first and last name, I added to it to explain what

happens to first and last name in this situation.

I was not able to properly reproduce and test this manually because I 

could not get a LDAP server up and running.
I have written a unit test that provides the modified function, 

get_or_create_user(), with a user that has a full name containing no

spaces and verifies that the first and last name are assigned as

expected.

This test passes with this fix, and fails on 2.5.x without the fix.