Switching to MVCC for uuid test to avoid lock-exceptions.
Fix for failing unit test
ACT-1629: Make BpmnDeployer pluggable in the ProcessEngineConfigurationImpl
Updated documentation for using expressions.

Added remark that users can use expressions in text fields of properties
belonging to CustomServiceTasks.

Also removed reference to older versions of Eclipse for developing
extensions.
Added check for history-level to be able to test comments or not