BS-7345
Add is multiple in process definition model
BS-8969, update database schema for mutliple references
Merge remote-tracking branch 'origin/master' into BS-7282_BizData_Multiple

Conflicts:
	bpm/bonita-core/bonita-process-definition/bonita-process-definition-impl/src/main/java/org/bonitasoft/engine/core/process/definition/model/builder/ServerModelConvertor.java
Merge branch 'master' into 'BS-7282_BizData_Multiple'
BS-8969, fix typo in Oracle drop tables script
Merge branch 'master' into 'BS-7282_BizData_Multiple'
Merge branch 'master' into 'BS-7282_BizData_Multiple'
Merge branch 'master' into 'BS-7282_BizData_Multiple'
Merge branch 'BS-7282_BizData_Multiple' into 'master'