Eliminate the need for a deployment branch

[yujiberra]

Most of the deployment configuration can be done with environment variables, but currently a few things require direct changes to files, and are managed by having a deployment branch on someone's machine.

Doing the following would make this unnecessary, and allow someone to switch between deployment and local testing simply by changing environment variables:

• Set the password in tomcat-users.xml with an environment variable
  • could be done with sed in Dockerfile
• Move the paths used for some volume mappings in Dockerfile to a environment variables
• Set up the right nginx/default.conf depending on an environment variable
  • could be done with sed, or by just generating the file (since it's one line) in Dockerfile