0.0.21 / 2017-02-20

[FEATURE] Hibernate collector added
[FEATURE] Log4j v2 collector added
[FEATURE] Guava cache collector added
[FEATURE] Caffeine cache collector added
[FEATURE] JVM version information added to default exports
[FEATURE] Allow setting name and help in build()
[FEATURE] Convenience no-labels methods added for get()
[BUGFIX] Ensure writer is closed in servlet handler
[ENHANCEMENT] Performance improvements to exposition

In addition, the README now contains extensive example usage.