RF: log all logging output from fail2ban-client to stderr. Close #264

otherwise it
1. 'interferes' with meaninful output of the client
2. if ERROR is logged it better go to stderr and separating ERROR from other levels is not that transparent with python's logging
ENH/RF: remove __readJailConfig in favor of __readConfig + catch/error exceptions while reading the configuration
ENH: raise an exception if not a single file was found for the jail. Close #63
Changelog entries with close statements for recent changes
ENH: allow_no_files option for jail's convert to allow testing of stock jail.conf
Merge pull request #265 from yarikoptic/master

Improve fail2ban-client errors logging/handling -- fail if no log file could be read, dump logs to stderr