Installation as Docker stack

[jussiarpalahti]

Preliminary issue

• Install and configure Docker based stack for Oskari frontend and server
• Support environment variables as config
• Investigate full stack including Postgres/PostGIS and Geoserver

[ZakarFin]

Adding links related to this from Gitter:

• https://github.com/jussiarpalahti/oskariexp
• https://hub.docker.com/r/jussiarpalahti/oskari

[ZakarFin]

Everything that can be configured with oskari-ext.properties can be configured as environment variables since version 2.6: #262 (https://github.com/oskariorg/oskari-server/pull/789)

[rekjuh]

@ZakarFin wasn't there an update on this just lately?