conference_item missing from types list

[goetzk]

conference_item is currently missing from typemap. I'm not entirely sure what we should call it - would it be a collection or should we use DataCites "Other" type and come up with a value?

For testing we're using collection but I'm hoping for second opinions before making that default for everyone.

$c->{datacitedoi}{typemap}{conference_item} = {v=>'Conference or Workshop Item', a=>'Collection'};

This is the type I referenced just now in de45ae9 .