Store the execution branch on work orders

Add a new property on WorkOrder that will hold the execution's branch
information. It will be set as soon as a package is sent to execution on a
package and registered on WorkOrderHistory.

Change-Id: Iee7b85a952f0c70c22dcd9f4bc80ebd430b22632
Filter available sellables by default on searchs

Also, add an api on search dialog for easy creation of Sellable.status filter,
just like we have for branches, payment, credit provider, etc

Change-Id: I86f90c4d26e15112476d92cc0b9e2d4770396ab6
Merge "Filter available sellables by default on searchs"