Clarifications on EML 410 Ballot

[David Webber <david.webber@oracle.com>]

Noticed that EML 410 proposaltext should be mandatory and proposal identifier attribute - currently they are marked optional.  The 
parent is optional of course - but if they choose that - then you need to have some text - can't be empty!

Similarly - there's a bug in schemas that makes it so in one part of EML 410 it shows Logo and URL as 1 to many occurrences - whereas it
is marked as zero to many everywhere else - e.g. optional, repeatable.  Need to adjust so they are optional, repeatable everywhere.

DW