Removed TaskDefinition: finally got rid of this bad idea of a class. Switched the implementations using it to determine it at runtime (consitent with all the rest).

Massively Cleanup Up TaskEntity: making it what it should be, a container for data and not a central hub for all kinds of operations (slightly overreacted).

Passing the processEngineConfigurationImpl to the entity/data managers on instantiation instead of relying on the Context lookup.

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)

# By sasdbm
# Via Joram Barrez (2) and sasdbm (1)
* 'activiti6' of https://github.com/Activiti/Activiti:
  Remove duplicate semi-colon
  Fix string concatenation when used as argument of append() call

Fix string concatenation when used as argument of append() call

Remove duplicate semi-colon

Fix for failing Oracle QA

# By sasdbm
# Via Tijs Rademakers (1) and sasdbm (1)
* 'activiti6' of https://github.com/Activiti/Activiti:
  Remove unused imports in engine project

Refactoring the persistence: splitting of persistence specific code in the EntityManager classes into a DataManager class.
The EntityManager -> EntityManagerImpl  now each have a dedicated DataManagerImpl that contains all the MyBatis specific code,
effectively making it possible to plug that layer with some other implementation.

Note: Still need to check the usages of DbSqlSession in the behaviors/commands, but those should be easily portable too.

Remove unused imports in engine project

# By Tijs Rademakers (4) and sasdbm (1)
# Via Tijs Rademakers
* 'activiti6' of https://github.com/Activiti/Activiti:
  Manual merge of pull request 656
  Move to Activiti 6 beta 2 snapshot version
  Release notes + migration docs changed for Activiti 6 Beta 1 release
  Move to 6.0.0.Beta1 version
  Fix string concatenation when used as argument of append() call

Fix string concatenation when used as argument of append() call

Disable javadoc generation on -Pcheck (+2 mins extra!) and fix build script to add java8 profile when building on jdk 8