[minor] Move default URL closer to the actual code.
[fix] Started work on double emit prevention.
[minor] Also allow options.url/options.uri as connection URL

This is a small addition to the logic that was introduced in edd07f2ad7f0b656de82bacb777fee6be540e21b
[test] Added missing test for the spark.readyStateChange event
[doc] Fix broken FAQ links
[test][minor] Add a very little improvement for the spark.readyStateChange event test