Make it possible to set input parameters on an automation chain

Parameters of the automation chain can be edited in a Tab on the automation chain screen.
User uses the same interface as for editing a schema (beside we need to correctly define available parameter types).
The information set by the user on this tab is used to complete the contribution of the chain, following the principle define on this documentation page about automation chain parameters:
http://doc.nuxeo.com/x/8QAz