Cleaned document picker templates.
Enhanced FormsManager:
- added cascadeEditor() method to ease the cascading of a document (existing or new)
- added cascadeEdit(doc) and cascadeCreate(modelName or doc) in Editors' scope (directly available in the template).

Enhanced Editors: added possibility to hide a section in the MainMenu when a document is being created (add 'hide-when-create="true"' on the <fieldset/> in the Editor template).
Merge pull request #223 from fredericbonjour/Admin

 Enhanced FormsManager (cascade process) and Editors.
- Fixed an issue in FormsManager.cascadeEditor() when a new empty Document is given.
- Added Utils.duplicateDocument().
- Added cascadeDuplicate() on Editors' scope and in <rbs-document-list/> scope.
Merge pull request #224 from fredericbonjour/Admin

Added document duplication features.
Refactoring Change\Commands namespace.
Fix GetDocumentTags Rest action query
Fixed broken document creation.
Merge pull request #226 from fredericbonjour/Admin

Fixed broken document creation.
Merge pull request #225 from inthause/documents

Refactoring Change\Commands namespace.
[NEW] getNewReadonlyDocument on TestCase.
[NEW] Price list on products
[NEW] Improve taxes section on billingArea