New dockerfiles

[miguelpeixe]

• avoid removing apt lists and reupdate (unify apt installs)
• chown on entrypoint
• shrink env into 1 layer
• put domegis files on /src directory
• dont compile mapnik fomr source (using v3.0.9 from ubuntu rep and let it handle its deps)

Reduced docker hub building time from over 2 hours to 18 minutes and 80mb less size (compressed)