Add loggregator logging to build plugins.

* Changed `streamRecentLogs()` to `getRecentLogs()`; changed it to collect log entries, sort by timestamp, and return log entries as a list. 
* Changed Gradle `cfLogs` task and Maven `cf:logs` goal to tail streaming logs. 
* Added Gradle `cfRecentLogs` task and Maven `cf:recentLogs` goal.