Also rename properties from 'Torperf' to 'Onionperf'.

src/main/java/org/torproject/collector/Main.java

src/main/java/org/torproject/collector/conf/Annotation.java

...ain/java/org/torproject/collector/conf/Configuration.java

src/main/java/org/torproject/collector/conf/Key.java

src/main/resources/collector.properties

src/test/java/org/torproject/collector/MainTest.java

...est/java/org/torproject/collector/cron/SchedulerTest.java