Improve error messages

[daknob]

The following line:

turnin/src/turnin.c

Line 235 in d2b800d

perror("seteuid");

as well as this:

turnin/src/turnin.c

Line 255 in d2b800d

perror("seteuid");

lack the class and user parts of the error message.

It's a quick PR to add them, and make error reporting better :)

[alx01011]

@daknob Is a string format such as classx: userx: setuid: error acceptable?

[daknob]

I think so. Even seteuid: class and seteuid: user without any variables are better than this :)

[zakkak]

Closed by #51