Support upgrading/downgrading widgets and operators from the wiring view

[aarranz]

Currently WireCloud support upgrading/downgrading widgets in the workspace view. This support should be extended to operators allowing users to upgrade and downgrade operators on the wiring editor view. In addition, users should also be able to upgrade/downgrade widgets using the wiring editor view.

• Implement the support for upgrading operators using WireCloud's JavaScript code. This include refactoring current code for handling missing operators that now should be considered as upgrading the operator from/to a missing operator.
• Update the user interface (the wiring editor) to provide the new functionality
• Fix wiring logs