MailServer pruning was implemented as a separate command but that required stopping a mail server and executing the command manually. This change builds pruning into MailServer and can be set using MailServerDataRetention in WhisperConfig.
add mailserver cleaner
use memstorage for leveldb in tests
avoid write if batch size is 0
add comments
add cmd/statusd-prune
rmeove batch size var in prune method
validate range values
pass only flag name to missingFlag
refactor Cleaner.prune method
update batch not to be a pointer
removed extra batch counter increment
don't increment counter if batch returns errors
add README
Adam Babik
Dmitry
Andrea Franz
Adrià Cidre