Failover options specified in uri string take precendence over the options argument on the constructor
Support nested arrays and objects in failover uri query string
Support connect[pfx|key|cert|ca] filename options. Use ssl if ssl scheme is specified
Track the last connect error and pass it along with the failover error object and include the last error message in the failover error message
Use tls.connect if options.ssl is set
Implement support for unix:// scheme