Remove grpc_java dependency and java_proto rules. (#214)

This is so that Envoy can consume opencensus-proto without adding
a dependency on grpc_java.

src/WORKSPACE

@@ -17,17 +17,6 @@ workspace(name = "opencensus_proto")
 load("@bazel_tools//tools/build_defs/repo:git.bzl", "git_repository")
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 
-# Import grpc_java for java_grpc_library().
-git_repository(
-    name = "grpc_java",
-    remote = "https://github.com/grpc/grpc-java.git",
-    tag = "v1.22.1",
-)
-
-load("@grpc_java//:repositories.bzl", "grpc_java_repositories")
-
-grpc_java_repositories()
-
 # Import grpc for cc_grpc_library().
 http_archive(
     name = "com_github_grpc_grpc",

src/opencensus/proto/agent/metrics/v1/BUILD.bazel

@@ -14,7 +14,6 @@
 
 package(default_visibility = ["//visibility:public"])
 
-load("@grpc_java//:java_grpc_library.bzl", "java_grpc_library")
 load("@io_bazel_rules_go//proto:def.bzl", "go_proto_library")
 load("@com_github_grpc_grpc//bazel:cc_grpc_library.bzl", "cc_grpc_library")
 
@@ -40,17 +39,6 @@ cc_grpc_library(
     grpc_only = True,
 )
 
-java_proto_library(
-    name = "metrics_service_proto_java",
-    deps = [":metrics_service_proto"],
-)
-
-java_grpc_library(
-    name = "metrics_service_grpc_java",
-    srcs = [":metrics_service_proto"],
-    deps = [":metrics_service_proto_java"],
-)
-
 go_proto_library(
     name = "metrics_service_proto_go",
     proto = ":metrics_service_proto",

src/opencensus/proto/agent/trace/v1/BUILD.bazel

@@ -14,7 +14,6 @@
 
 package(default_visibility = ["//visibility:public"])
 
-load("@grpc_java//:java_grpc_library.bzl", "java_grpc_library")
 load("@io_bazel_rules_go//proto:def.bzl", "go_proto_library")
 load("@com_github_grpc_grpc//bazel:cc_grpc_library.bzl", "cc_grpc_library")
 
@@ -41,17 +40,6 @@ cc_grpc_library(
     grpc_only = True,
 )
 
-java_proto_library(
-    name = "trace_service_proto_java",
-    deps = [":trace_service_proto"],
-)
-
-java_grpc_library(
-    name = "trace_service_grpc_java",
-    srcs = [":trace_service_proto"],
-    deps = [":trace_service_proto_java"],
-)
-
 go_proto_library(
     name = "trace_service_proto_go",
     proto = ":trace_service_proto",