Add stream config when one of the vars is defined

[pieterlexis]

Before, nginx_mainline_repo was used to identify a modern enough nginx.
Unfortunately, distros are catching up (e.g. Debian Stretch) and support
the streams module.

If nginx_stream_params or nginx_stream_configs are not empty, a stream
block is included in nginx.conf.

Closes #160

[jdauphant]

@pieterlexis Does it work with the default values ? (empty list and empty map)

ansible-role-nginx/defaults/main.yml

Line 33 in 21e3d1c

nginx_stream_params: []

ansible-role-nginx/defaults/main.yml

Line 45 in 21e3d1c

nginx_stream_configs: {}

[pieterlexis]

As far as I know, empty lists and dicts evaluate to False:

Python 2.7.13 (default, Dec 21 2016, 07:16:46) 
[GCC 6.2.1 20160830] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> bool([])
False
>>> bool({})
False
>>> bool({} or [])
False
>>> bool({} or ['aaa'])
True
>>> bool({'aaa':'bbb'} or [])
True

I'll test this on a machine without streams after the weekend :)

[jdauphant]

@pieterlexis I just check, it's evaluate to false with ansible

[jdauphant]

Thanks for you help :)