Piwik 2.2.1 发布，此版本是个小版本，同时也是个更稳定的版本，建议更新。
All your settings will be saved and restored the next time you visit
any report in Piwik.
Several bugs were fixed in the Installation process which affected a
subset of users.
a Referrer spam blacklist feature was implemented
Developers: Period::factory() is deprecated, please use Period\Factory::build() instead
(released in 2.2.0) Event Tracking:
track your custom events with Piwik.