Update HoneyBadger Logger to send stacktrace

[stnguyen90]

It would be really nice to be able to pass the stack trace along. Check out how it's implemented in Sentry and how we call this in Appwrite.

Originally posted by @stnguyen90 in #19 (comment)

[stnguyen90]

The payload for a backtrace should look like:

    "backtrace":[
      {
        "number":"4",
        "file":"/crywolf/app/controllers/pages_controller.rb",
        "method":"runtime_error",
        "source":{
          "2":"",
          "3":"  def runtime_error",
          "4":"    raise RuntimeError.new(\"This is a runtime error, generated by the crywolf app\")",
          "5":"  end",
          "6":""
        }
      },
      {
        "number":"4",
        "file":"/gems/1.9.3-p194/lib/ruby/gems/1.9.1/gems/actionpack-3.2.8/lib/action_controller/metal/implicit_render.rb",
        "method":"send_action"
      }
    ],