Clearly display to the user which newsletter is currently being used by the Newsletter Block. Currently when editing the block it displays the first available newsletter by default. This is confusing for the user that may think its block was badly configured. It now clearly display the current chosen newsletter. Task ID #2192807 Closes #47959 Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>