Conversation.markRead: Remove checks for unread
Conversation.markRead: Remove checks for unread

We will now always attempt to mark things unread if this method. If the
conversation's unreadCount gets out of date, set to zero, we will still
do it. If we go through the motions, and nothing is newly marked read,
we will still set the unreadCount to zero.
nrizzio/Signal-Desktop,nrizzio/Signal-Desktop,nrizzio/Signal-Desktop,nrizzio/Signal-Desktop