bump atc
bump atc

Submodule src/github.com/concourse/atc 83067d7..0483fd1:
  > use non-minified js for debuggability

concourse/concourse,cjcjameson/concourse,zachgersh/concourse,concourse/concourse,zachgersh/concourse,zachgersh/concourse,concourse/concourse,concourse/concourse,cjcjameson/concourse,concourse/concourse,cjcjameson/concourse