Search for "mainflux-nginx" instead of "nginx"
Search for "mainflux-nginx" instead of "nginx"

Fixes #130 where the script sees non mainflux-nginx container(s) and
assumes mainflux-nginx is already pulled/created.

Signed-off-by: bzub <2901171a854698990acab827b97dd7bb8cb1e564@gmail.com>

drasko/mainflux,Mainflux/mainflux-lite,drasko/mainflux,drasko/mainflux