Fixes for Docker build

- add runtime dependency on git
- set ONOS_ROOT before doing build
- Add top level directory to grpc proto compiler include directories

Change-Id: I6e7a119a122f708988cce28090c9bc7011808b78
diff --git a/protocols/grpc/proto/BUCK b/protocols/grpc/proto/BUCK
index b1be821..f4a4033 100644
--- a/protocols/grpc/proto/BUCK
+++ b/protocols/grpc/proto/BUCK
@@ -15,7 +15,7 @@
 
 grpc_jar(
     proto_match_patterns = ["*.proto"],
-    proto_paths = ["$ONOS_ROOT/protocols/grpc/proto/"],
+    proto_paths = ["$ONOS_ROOT/protocols/grpc/proto/", "$ONOS_ROOT"], #FIXME should not have to include ONOS_ROOT top level here
     protoc_version = PROTOC_VER,
     plugin_version = GRPC_VER,
     deps = COMPILE_DEPS,
@@ -23,4 +23,4 @@
 
 project_config(
     src_target = ':onos-protocols-grpc-proto'
-)
\ No newline at end of file
+)