Reorder some sections.

I think the new ordering makes more sense when reading the document in
a first run context.
Document and add an example for setAction()
Merge pull request #2035 from cakephp/controller-cleanup

Reorder some sections.
Remove duplicate and confusing ControllerTestCase docs.
[fr] Update Entities.rst

ligne 149: Est-ce que ces majuscules étaient vraiment volontaires?
[fr] Update behaviors.rst

ligne 7: suggestion de formulation
Merge pull request #2039 from caBBAlainB/patch-24

[fr] Update behaviors.rst
Merge pull request #2038 from caBBAlainB/patch-23

[fr] Update Entities.rst
Merge pull request #2036 from antograssiot/3.0

[fr] typos and formating.
Fixing explanation for the enabled cache config
update`.::` to `. ::` to avoid `:` being displayed
[fr] follow #2035, 1f02e451