working zeus.json and fixes custom_plan.rb for zeus 0.13.3.rc2

custom_plan.rb

require 'zeus/rails'

class CustomPlan < Zeus::Rails
    def rspec
      RSpec::Core::Runner.disable_autorun!
      exit RSpec::Core::Runner.run(ARGV)
    end
end

zeus.json

{
  "command": "ruby -rubygems -r./custom_plan -eZeus.go",

  "plan": {
    "boot": {
      "default_bundle": {
        "development_environment": {
          "prerake": {"rake": []},
          "runner": ["r"],
          "console": ["c"],
          "server": ["s"],
          "generate": ["g"],
          "destroy": ["d"],
          "dbconsole": []
        },
        "test_environment": {
          "test_helper": {"test": ["testrb"], "rspec": []}
        }
      }
    }
  }
}