Caduceus panics with non-utf string for event name

[ilawjr]

If you attempt to pass in a string that cannot be parsed correctly by the underlying metrics, caduceus panics.

panic: label event: value "raw.kestrel.reports\xedNetworkDevicesStatus" is not valid UTF-8

vendor/github.com/prometheus/client_golang/prometheus.(*CounterVec).With(0xc00000ea08, 0xc05d2c21b0, 0x6, 0xc05d2c21b0)
/root/rpmbuild/BUILD/caduceus-0.1.3/src/vendor/github.com/prometheus/client_golang/prometheus/counter.go:217 +0x79
vendor/github.com/go-kit/kit/metrics/prometheus.(*Counter).Add(0xc010491dc0, 0x3ff0000000000000)
/root/rpmbuild/BUILD/caduceus-0.1.3/src/vendor/github.com/go-kit/kit/metrics/prometheus/prometheus.go:45 +0x5c
main.(*CaduceusOutboundSender).send(0xc001826900, 0xc01628c590, 0xe, 0xc01628c578, 0x4, 0xc0a0141b00)
/root/rpmbuild/BUILD/caduceus-0.1.3/src/caduceus/outboundSender.go:537 +0xa44
created by main.(*CaduceusOutboundSender).dispatcher
/root/rpmbuild/BUILD/caduceus-0.1.3/src/caduceus/outboundSender.go:444 +0x342

[schmidtw]

This seems to be something that should be done in wrp-go based on some local feedback I got.

xmidt-org/wrp-go#25

We also should make the outgoing goroutine panic tolerant as well.

[kristinapathak]

This is fixed.