set script-encoding to utf-8 and use local dir for lib before search system
List whether source is usual, notify user of special handling

also list :usual as attr_reader in Source
fix elseif: delete sync-back-ok if sync_back_to_maildir has been set to false
Merge pull request #1 from gauteh/missing_sync_back_ok

Notify user of special handling for unsual sources and list whether source is usual