Remove userId from participant attributes
Add TaskShortInfo
Merge branch 'refactoring' into step-2

Conflicts:
	src/main/java/fr/xebia/xke/dto/ProductShortInfo.java
	src/main/java/fr/xebia/xke/dto/TaskShortInfo.java
	src/main/java/fr/xebia/xke/service/impl/BlotterServiceImpl.java
	src/main/java/fr/xebia/xke/service/impl/TaskHelper.java