Squeezelite players don't successfully register on mysqueezebox.com anymore

```
Steps to reproduce the problem?
1. Create a new mysqueezebox.com account
2. Association your LMS to that account
3. Start a Squeezelite player on that LMS, and notice it won't show up (the
mac address) in the "Players" tab when logged into that mysqueezebox.com
account.

Previously, registration would work. It looks like there has been recent
changes to mysqueezebox.com to verify the uuid field of the registration
request, because not the registration fails with a message that the request is
"missing UUID".

It's reproducible with v1.6.3 on a Mac and on Linux ARM.

Note, running SqueezePlay on the same box successfully registered the player.
Also note that it contains a UUID in the request.

Here is an example of the request and response for both SqueezePlay (working)
and SqueezeLite (not working):

SqueezePlay:
-->
{"client":"c5:2d:03:23:36:f5","deviceid":"12","since":"1415980267","name":"Squee
zePlay","rev":"7.7.2-r9599M","model":"squeezeplay","uuid":"3fddf16ae82ef95a5f132
a21d6c5cb1b"}
<-- {"next_sync":17280,"timestamp":1415980886,"prefs":{},"name":"SqueezePlay"}

SqueezeLite:
-->
{"client":"7c:20:66:0b:e8:66","deviceid":"12","since":"-1","name":"SqueezeTestLi
te","rev":0,"model":"squeezelite","uuid":null}
<-- {"ok":0,"error":"No such player: 7c:20:66:0b:e8:66 (Software player,
missing UUID)"}
```

Original issue reported on code.google.com by `justin.m...@clarecontrols.com` on 14 Nov 2014 at 6:24