This is hackish and hardcoded for now because it's only for bt5 Documents. It
should be more generic (for non-bt5 Documents), but this is tricky from a
bootstrap point of view, so keep it simple for now.

Also, move code from Extension Component to Component and make it more generic
in order to be used for Document Component.

At most until everything has been implemented.

* Implement Extension Component.
  * Complete ExtensionComponent view.
  * Add component_interaction_workflow to reset erp5.component when modifying an Extension Component.

For now this is a global reset, meaning that everytime a component is changed,
all the component are reset, which is terrible from a performance point of
view.

Return a safe html selenium test code (which always fails) to indicate a problem when download a test. This will prevent Zelenium get Stalled during the launch.

Follow up commit e0855913

Code cleaned up from not needed variables.