fix transaction deadlock when deleting pending file attachment
populate pending file attachments properly, consolidate AATTMessagePlus init code
index > 0, not 1

this is left over from when channel ID was used as the first param
fix.
completionBlock should be called when file is already being uploaded

i guess? maybe no completion block, but instead a notification?
fix bug from previous messages methods refactoring.

should select all cols
load messages needing pending file, send unsent messages after file uploads
add assertion to check if pending file exists
the message that triggers the file upload will have continue to get send attempts after file upload