Push Functest API doc to artifact

Note that it is not the final goal
The final goal is to integrate api doc into Functest
developer guide
This will be triggered from opnfvdocs and replace the current
developer guide:
http://docs.opnfv.org/en/stable-danube/submodules/functest/docs/testing/developer/devguide/index.html

This patch allows to have an up-to-date api docs on the artifact after
functest merge
http://artifacts.opnfv.org/functest/docs/

Change-Id: I91256add29ce9eadd66764c2234da1d60981dd31
Signed-off-by: Morgan Richomme <morgan.richomme@orange.com>
Signed-off-by: Sakala Venkata Krishna Rohit <rohitsakala@gmail.com>
Signed-off-by: Morgan Richomme <morgan.richomme@orange.com>