Readthedocs failed to render Promenade exceptions with error:
> WARNING: autodoc: failed to import exception 'xxx' from module
> 'promenade'; the following exception was raised: No module
> named 'falcon'
Trying to add Promenade requirements to the installed requirements list,
so that Readthedocs has all modules, including those needed for the
Promenade itself.
Unify docs building by utilizing Zuul docs-on-readthedocs template job.
Cosmetic readability changes:
1. combined all Makefile .PHONY targets into one
2. merged multiple LABEL instructions in Dockerfile into one
Change-Id: I731ee3426a631fa765f13ba7091dcb4b9ebd0353
d12927a156