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

ACT-1581: Refactor ProcessDiagramGenerator to take BpmnModel as input instead of ProcessDefinitionEntity + ACT-1580: Add method to retrieve BpmnModel (Pojo version of BPMN 2.0 process) to RepositoryService

Refactoring DeploymentCache: introducing DeploymentEntityManager and DeploymentManager. Made DeploymentCache an interface for pluggability

ACT-741 refactoring persistence: refactoring IdentitySession and Tasksession into appropriate entity based XxxxManagers

ACT-60 switching back from activity instances to executions: allowed multiple order by criteria in queries

ACT-60 grouping all deployment and process definition mgmt into RepositoryService and RepositorySession (breaks build)