fix(codec): Remove custom content-type (#104)

This removes custom content-types in favor of
just using `application/grpc`. There is some
confusion around the specification but most
grpc implementations ignore the `+` and
anything after.

tonic-examples/Cargo.toml

@@ -52,6 +52,10 @@ path = "src/tls_client_auth/server.rs"
 name = "tls-client-auth-client"
 path = "src/tls_client_auth/client.rs"
 
+[[bin]]
+name = "gcp-client"
+path = "src/gcp/client.rs"
+
 [dependencies]
 tonic = { path = "../tonic", features = ["rustls"] }
 bytes = "0.4"
@@ -68,5 +72,8 @@ serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 rand = "0.7.2"
 
+# Required for wellknown types
+prost-types = "0.5"
+
 [build-dependencies]
 tonic-build = { path = "../tonic-build" }