Stack overflow with cycles.

[dankelleher]

It looks like this issue has re-appeared. Minimal use case:

const loggly = require("loggly");

const client = loggly.createClient({
  token: <loggly-token>,
  subdomain: <subdomain>
});

const circular = { a : "123"};
circular.b = circular;

client.log(circular);

gives:

RangeError: Maximum call stack size exceeded
    at Object.common.serialize (/.../tmp-loggly-testcase/node_modules/loggly/lib/loggly/common.js:154:29)
    at Object.common.serialize (/.../tmp-loggly-testcase/node_modules/loggly/lib/loggly/common.js:187:21)
    at Object.common.serialize (/.../tmp-loggly-testcase/node_modules/loggly/lib/loggly/common.js:187:21)

[dankelleher]

PR here: #77