Added context
Refactored until 1st exercise
Changed exercise on wf (impacts structure templates)
Removed duplicate slides about nodes
Changed general and variables node config slides
Refactored until 2nd exercise (impacts structure templates)
Refactored task general tab
Refactored until wf tasks exercise
Started wf variables refactoring
Refactored until last basic exercise
Renamed slides title to gain coherence
Added advanced set of slides on wf
Merge pull request #1 from nuxeo/workflow-refactoring

Workflow refactoring