If backends have a failure or something, don't discard the messages,
wait half a second and then try sending them again.

This solves an issue reported by 'cloudhead' in IRC where deep lists
weren't being flattened when printed with format specifiers like ~s ~p
and ~P, all of which should flatten the list.

Adt add simple rotation

IBM punchcards rejoice! Basho supports your right to continue to affect
how we format source code :)

Adding date spec parsing and calculation of when a spec indicates a file
next needs to be rotated.

Fix sporadic EUnit test failures: try to sync via gen_event:which_handlers(), increase some sleep times

az558