Disable metrics_service, cannot publish with grpcio dependency

Author: jackcmay

Cargo.lock

@@ -10,7 +10,7 @@ edition = "2018"
 
 [dependencies]
 futures = "0.1.28"
-grpcio = { version = "=0.5.0-alpha.4", default-features = false, optional = true }
+# grpcio = { version = "=0.5.0-alpha.4", default-features = false, optional = true }
 hyper = "0.12.34"
 lazy_static = "1.3.0"
 serde_json = "1.0.40"
@@ -24,5 +24,5 @@ rusty-fork = "0.2.1"
 assert_approx_eq = "1.1.0"
 
 [features]
-service-metrics = ["grpcio"]
-default = ["service-metrics"]
+# service-metrics = ["grpcio"]
+# default = ["service-metrics"]