* DW-1667 - created instance will return with status CREATED and no start date

* DW-1667 - fixed tests for new status CREATED/STARTED

* DW-1667 - fixed IT

My quarterly pass through the code looking for unused imports.

added start time on execution entities
added started by on execution entities

exposed on ExecutionQuery and ProcessInstanceQuery

Did a sweep through all EntityImpl classes. Added no-args constructor to be consistent with all entity classes. Removed unused constructors.

* ProcessInstance
* Execution (Process/SubProcess)
* HistoricProcessInstance

In addition, this change includes an improvement to add fallback support for resolving a localization.

Refactored all entity classes: added an interface for each entity, such that alternative data stores can swap out the entity objects with more fitting ones (eg with annotations like Neo4j, JPA, etc or other mechanisms. Internally, only the entity interface is used)

Format back to 2 spaces for now, merging back from Activiti 5 is really an issue with spacing differences

Fixing QA and database quirks when handling null values in unique constraint in the context of multi tenancy.

- More consistent member ordering.

Added SetProcessDefinitionVersionCmd as discussed in http://forums.activiti.org/en/viewtopic.php?t=2918

Added query possibility in HistoricProcessInstance to search for process instances that have a specific super process instance.
This makes it possible to retrieve sub processes created via a call activity based on the parent process instance id.

ACT-329 Also enabled HistoricProcessInstance.startActivityId and endActivityId on plain startProcessInstance (previously it was only on submitStartForm)