Enable comma escaping, unicode chars in classlists

Classlists files as processed by the addcourse script can't deal with users
who, for one reason or another, has a comma in either their first or last
name. Using the Text::CSV module for CSV parsing instead of split() enables
comma escaping values by putting them in double quotes.

Users who have non-ASCII characters in their name gets their name (e.g.:
Frøystein) mangled after going through addcourse. This commit forces Perl
to open the the classlist file with UTF8 encoding. This way the unicode
characters survive intact into the database.