add Dockerfile, support for default ADIF_URL

[robertlestak]

• Adds a Dockerfile for containerization and easier deployment (if that's your prerogative)
• Adds a scripts/build.sh script which consumes an ADIF_URL env var to update the index.html file with the default ADIF URL.
  • When set, this will always take precendee over the url query string param, enabling it to be used to solely display desired ADIF without allowing user to change URL param

[stephenhouser]

I know this is here, just have not decided if I want to merge or not.

Changes in this PR:

• Setting a static ADIF URL to load which disables ability to load other URLs. (I see where this would be useful to folks just wanting to display their own maps)
• Setting the Title/Brand on the page header.
• Adding Dockerfile and k8s launch/configuration examples.