Create a pop up for when Dave deselects some attributes

add a boolean in contractInputGenerator to know if all attributes are
generated or not

add a pop up on finish (and finish and add)

Conflicts:
	bundles/plugins/org.bonitasoft.studio.contract/src/org/bonitasoft/studio/contract/core/mapping/RootContractInputGenerator.java
	bundles/plugins/org.bonitasoft.studio.contract/src/org/bonitasoft/studio/contract/ui/wizard/ContractInputGenerationWizard.java