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

Act-1691: programmatic update of process definition category + fixed to ScriptTaskListener on recent jdk's

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

history reporting done from withing the engine

ACT-1202: Tackled the problem which strangely did not fail on local H2, history entry is created in ProcessDefinitionEntity as well

Added pool and lanes parsing and rendering on diagram + added missing "drop" statements for new indexes added

ACT-655, ACT-661, ACT-667: Clarified form exception, Exposed Process documentation, diagram cutoff bug

ACT-15: added example of boundary error catch to distro. Added drawing support in for error event in deployer. Introduced shortcut to reference errors.

ACT-352 Fixing lazy initialization of historic variable updates.  Also fixed configuration of history

- Add support for namespace prefix
- Refactor input and output associations
- Enhance structure hierarchy