Add tests for the template.go file.

This also adds an error condition that I hadn't previously considered.
If there is a streaming API swagger doesn't currently support it. I
handle that now with an error.

Makefile

@@ -34,6 +34,7 @@ OPTIONS_PROTO=$(GOOGLEAPIS_DIR)/google/api/annotations.proto $(GOOGLEAPIS_DIR)/g
 OPTIONS_GO=$(OPTIONS_PROTO:.proto=.pb.go)
 
 PKGMAP=Mgoogle/protobuf/descriptor.proto=$(GO_PLUGIN_PKG)/descriptor,Mgoogle/api/annotations.proto=$(PKG)/$(GOOGLEAPIS_DIR)/google/api,Mexamples/sub/message.proto=$(PKG)/examples/sub
+SWAGGER_EXAMPLES=examples/examplepb/echo_service.proto
 EXAMPLES=examples/examplepb/echo_service.proto \
 	 examples/examplepb/a_bit_of_everything.proto \
 	 examples/examplepb/flow_combination.proto
@@ -67,8 +68,8 @@ $(EXAMPLE_DEPSRCS): $(GO_PLUGIN) $(EXAMPLE_DEPS)
 	protoc -I $(PROTOC_INC_PATH) -I. --plugin=$(GO_PLUGIN) --go_out=$(PKGMAP),plugins=grpc:. $(EXAMPLE_DEPS)
 $(EXAMPLE_GWSRCS): $(GATEWAY_PLUGIN) $(EXAMPLES)
 	protoc -I $(PROTOC_INC_PATH) -I. -I$(GOOGLEAPIS_DIR) --plugin=$(GATEWAY_PLUGIN) --grpc-gateway_out=logtostderr=true,$(PKGMAP):. $(EXAMPLES)
-$(EXAMPLE_SWAGGERSRCS): $(SWAGGER_PLUGIN) $(EXAMPLES)
-	protoc -I $(PROTOC_INC_PATH) -I. -I$(GOOGLEAPIS_DIR) --plugin=$(SWAGGER_PLUGIN) --swagger_out=logtostderr=true,$(PKGMAP):. $(EXAMPLES)
+$(EXAMPLE_SWAGGERSRCS): $(SWAGGER_PLUGIN) $(SWAGGER_EXAMPLES)
+	protoc -I $(PROTOC_INC_PATH) -I. -I$(GOOGLEAPIS_DIR) --plugin=$(SWAGGER_PLUGIN) --swagger_out=logtostderr=true,$(PKGMAP):. $(SWAGGER_EXAMPLES)
 
 examples: $(EXAMPLE_SVCSRCS) $(EXAMPLE_GWSRCS) $(EXAMPLE_DEPSRCS) $(EXAMPLE_SWAGGERSRCS)
 test: examples