Use a single port to route all traffic

[slemeur]

Goals

Along with the work done for the integration with Openshift, we need to unify this mecanism for Che.

The idea would be to embed a reverse proxy in order to allow the single-port strategy.
This will likely simplify the administration and configuration of Che/Codenvy by reducing the number of port necessary using a single one.

We would also let the user being able to configure the port to get exposed .

Linked Issues:

#1560
#4269
#3037

[slemeur]

Linking with Traefik issue: traefik/traefik#1257

[benoitf]

for Che, it's done

[slemeur]

Excellent !