directory structure change to work with glide

glide has its own requirements. My previous workaround caused me some
code checkin errors. Need to fix this.

weed/proto/Makefile

@@ -0,0 +1,4 @@
+TARG=../operation
+
+all:
+	protoc --go_out=$(TARG) system_message.proto

weed/proto/system_message.proto

@@ -0,0 +1,27 @@
+package operation;
+
+message VolumeInformationMessage {
+  required uint32 id = 1;
+  required uint64 size = 2;
+  optional string collection = 3;
+  required uint64 file_count = 4;
+  required uint64 delete_count = 5;
+  required uint64 deleted_byte_count = 6;
+  optional bool read_only = 7;
+  required uint32 replica_placement = 8;
+  optional uint32 version = 9 [default=2];
+  optional uint32 ttl = 10;
+}
+
+message JoinMessage {
+  optional bool   is_init = 1;
+  required string ip = 2;
+  required uint32 port = 3;
+  optional string public_url = 4;
+  required uint32 max_volume_count = 5;
+  required uint64 max_file_key = 6;
+  optional string data_center = 7;
+  optional string rack = 8;
+  repeated VolumeInformationMessage volumes = 9;
+  optional uint32 admin_port = 10;
+}