Update version handling in gradle build

[jessicasyu]

• Add version.properties file to track major, minor, and patch versions
• Add tasks to build.gradle to bump major, minor, and patch versions
• Add task to build.gradle to display version information (the version <major>.<minor>.<patch> and the "full" version <most recent tag>-<number of commits since most recent tag>-<current commit hash> used to name the jar
  • Once we actually start releasing versions, we can add an action that automatically keeps the version.properties tag and the git tag in sync
  • Current process is just to manually tag the commit with the version
• Update Dockerfile to take VERSION build arg