ZEN-11855: Address ZEP performance issues around concurrency

Conflicts:
	core/src/main/java/org/zenoss/zep/index/impl/EventIndexMapper.java
	core/src/main/java/org/zenoss/zep/index/impl/QueryBuilder.java
	core/src/main/resources/zeneventserver.conf
	core/src/test/java/org/zenoss/zep/index/impl/EventIndexDaoImplIT.java
	src/core/protocols/java/amqp-samples/src/main/java/org/zenoss/amqp/samples/ProducerTest.java
Merge pull request #19 from zenoss/concurrency_perf_fix

ZEN-11855: Address ZEP performance issues around concurrency