Dpawluk/close warn

Created a warning in the child ticket info display when creating a child ticket from a closed parent. I didn't want to be extra obtrusive or add another growl-like warning so instead the I added a message to the child ticket summary which will only display that once.

CC'ing @quokka @maximeprades 
please remove the strings from this file, en.json is enough, it will automatically be added there when translations are back