Hack: Hardcode paths to wellknown types

This is a hack to get grpc_cli working.
golang/protobuf#298

grpc_cli does not recognize the wellknown types. To get
grpc_cli to work, I adjusted the paths from the proper, language
agnostic, paths to the concrete, go specific, paths. I also adjusted my
repository to match the paths that the well known types were declaring
in their descriptors.

gen.go

@@ -14,7 +14,7 @@
 
 package trillian
 
-//go:generate protoc -I=. -I=$GOPATH/src -I=$GOPATH/src/github.com/googleapis/googleapis --go_out=plugins=grpc:$GOPATH/src trillian_log_api.proto trillian_map_api.proto trillian_admin_api.proto trillian.proto
+//go:generate protoc -I=. -I=$GOPATH/src -I=$GOPATH -I=$GOPATH/src/github.com/googleapis/googleapis --go_out=plugins=grpc:$GOPATH/src trillian_log_api.proto trillian_map_api.proto trillian_admin_api.proto trillian.proto
 //go:generate protoc -I=. --go_out=:$GOPATH/src crypto/sigpb/sigpb.proto
 //go:generate protoc -I=. --go_out=:$GOPATH/src crypto/keyspb/keyspb.proto
 //go:generate protoc -I=. -I=$GOPATH/src -I=$GOPATH/src/github.com/google/trillian/vendor/github.com/grpc-ecosystem/grpc-gateway/third_party/googleapis -I=$GOPATH/src/github.com/googleapis/googleapis/ --grpc-gateway_out=logtostderr=true:$GOPATH/src trillian_log_api.proto trillian_map_api.proto trillian_admin_api.proto trillian.proto

trillian.proto

@@ -23,7 +23,8 @@ package trillian;
 
 import "crypto/keyspb/keyspb.proto";
 import "crypto/sigpb/sigpb.proto";
-import "google/protobuf/any.proto";
+//import "google/protobuf/any.proto";
+import "github.com/golang/protobuf/ptypes/any/any.proto";
 
 // What goes in here?
 // Things which are exposed through the public trillian APIs.

trillian_admin_api.proto

@@ -24,8 +24,8 @@ package trillian;
 import "trillian.proto";
 import "crypto/keyspb/keyspb.proto";
 import "google/api/annotations.proto";
-import "google/protobuf/field_mask.proto";
-import "google/protobuf/empty.proto";
+import "github.com/google/protobuf/src/google/protobuf/field_mask.proto";
+import "github.com/golang/protobuf/ptypes/empty/empty.proto";
 
 // ListTrees request.
 // No filters or pagination options are provided.