pmd fixes, disabled one custom rule and made Configuration not abstract

conf/quality-config/pmd-ruleset.xml

src/main/java/teetime/framework/Configuration.java

src/main/java/teetime/framework/Execution.java

src/main/java/teetime/framework/IntraStageCollector.java

src/main/java/teetime/framework/RunnableConsumerStage.java

src/main/java/teetime/framework/TeeTimeThread.java

src/main/java/teetime/framework/ThreadService.java