[maven-release-plugin] prepare for next development iteration
fix typo in README
mark prepare() method as final
ack tuple after conditional push to disk
remove unnecessary call to hsync() when closing files
changed hdfs security config keys to hdfs.*
mark instance variables initialized in prepare() as transient
implement locking for file writes/rotation
Implement TimedRotationPolicy
ensuring the existence of keytab file before passing to Hadoop

Storm now offers the ability to use forwardable, renewable tickets to
authenticate to Hadoop. This commit makes it possible to use these
tickets rather than fixed keytab files, which are not ideal for
Kerberos principals representing end users.