Log Message:
2.0.4 -> 2.1.7

tons of bug fixes
new features:
  * pt-online-schema-change: Columns can now be renamed without data loss
  * pt-online-schema-change: New --default-engine option
  * pt-stalk: Plugin hooks available through the --plugin option to extend the \ 
tool's functionality
  * pt-table-checksum: Percona XtraDB Cluster support
  * pt-table-checksum: Implemented the standard --run-time option
  * Implemented the version-check feature in several tools, enabled with the \ 
--version-check option
  * pt-kill: Implemented --log-dsn to log info about killed queries to a table
  * pt-heartbeat: Implemented --recursion-method=none
  * pt-index-usage: MySQL 5.5 compatibility fixes
  * pt-log-player: MySQL 5.5 compatibility fixes
  * pt-online-schema-change: Added --chunk-index-columns
  * pt-online-schema-change: Added --[no]check-plan
  * pt-online-schema-change: Added --[no]drop-new-table
  * pt-online-schema-change: Implemented --recursion-method=none
  * pt-query-advisor: Added --report-type for JSON output
  * pt-query-digest: Removed --[no]zero-bool
  * pt-slave-delay: Added --database
  * pt-slave-find: Implemented --recursion-method=none
  * pt-slave-restart: Implemented --recursion-method=none
  * pt-table-checksum: Added --chunk-index-columns
  * pt-table-checksum: Added --[no]check-plan
  * pt-table-checksum: Implemented --recursion-method=none
  * pt-table-sync: Disabled --lock-and-rename except for MySQL 5.5 and newer
  * pt-table-sync: Implemented --recursion-method=none
  * Completely redesigned pt-online-schema-change
  * Completely redesigned pt-mysql-summary
  * Completely redesigned pt-summary
  * Added new tool: pt-table-usage
  * Added new tool: pt-fingerprint