Voice Client JS 1.9.5: Singapore Interconnect (sg1-ix) region support

You can now connect to our interconnect region in Singapore by setting the region option to sg1-ix. See https://www.twilio.com/docs/voice/client/regions for the list of supported regions. Note that with this release, to support new regions without requiring an SDK update, we have removed the check for the region name passed to `Device.setup`. If an unsupported region is supplied, `Device.on('error')` will be called.

For full changelog, visit the Voice JS Client release notes.