Convert to go modules; add ARI status check

All NATS responders now check the ARI client to make sure it is
connected before responding.

Fixes CyCoreSystems#25

go.mod

@@ -0,0 +1,32 @@
+module github.com/CyCoreSystems/ari-proxy
+
+go 1.12
+
+require (
+	github.com/BurntSushi/toml v0.3.1 // indirect
+	github.com/CyCoreSystems/ari v5.0.0-pre4+incompatible
+	github.com/fsnotify/fsnotify v0.0.0-20170329110642-4da3e2cfbabc // indirect
+	github.com/golang/protobuf v1.3.1 // indirect
+	github.com/hashicorp/hcl v0.0.0-20170509225359-392dba7d905e // indirect
+	github.com/inconshreveable/log15 v0.0.0-20171019012758-0decfc6c20d9
+	github.com/inconshreveable/mousetrap v1.0.0 // indirect
+	github.com/kr/pretty v0.1.0 // indirect
+	github.com/magiconair/properties v1.7.3 // indirect
+	github.com/mitchellh/mapstructure v0.0.0-20170523030023-d0303fe80992 // indirect
+	github.com/nats-io/gnatsd v1.4.1 // indirect
+	github.com/nats-io/go-nats v0.0.0-20170814154326-b4479c874d87 // indirect
+	github.com/nats-io/nats v1.5.0
+	github.com/nats-io/nuid v0.0.0-20170303150224-3cf34f9fca4e // indirect
+	github.com/pelletier/go-toml v0.0.0-20170817000623-4692b8f9babf // indirect
+	github.com/pkg/errors v0.8.0
+	github.com/spf13/afero v0.0.0-20170217164146-9be650865eab // indirect
+	github.com/spf13/cast v1.1.0 // indirect
+	github.com/spf13/cobra v0.0.2
+	github.com/spf13/jwalterweatherman v0.0.0-20170523133247-0efa5202c046 // indirect
+	github.com/spf13/pflag v1.0.0 // indirect
+	github.com/spf13/viper v1.0.2
+	github.com/stretchr/testify v1.2.1
+	golang.org/x/crypto v0.0.0-20190605123033-f99c8df09eb5 // indirect
+	gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 // indirect
+	gopkg.in/yaml.v2 v2.0.0-20170812160011-eb3733d160e7 // indirect
+)