Espruino Wifi Socket recovery

You'd normally get the builds from http://www.espruino.com/binaries/travis/master/, and it's the _wifi one. Looking at it, it seems like the build VM on travis actually failed for the WiFi this time (it happens sometimes even when there is no software fault). I'll push some more changes in a few minutes which will kick off the build again and it should work fine.

You shouldn't need a new firmware... I think the handling is ok - it does AT+CIPSEND then gets OK. It returns cb - the same function - so gets called back with > then it writes data and hopefully gets Recv ... and then SEND OK at which point it returns undefined which lets it carry on with other stuff