Synchronize protobuf with version used in rules_closure

Avoid fetching a potentially different version of protobuf-java and use
version that rules_closure transitively depends on.

Change-Id: Ief63f06cb531cd76e2bcf8c5623d653a5c1b69c7

WORKSPACE

@@ -228,12 +228,6 @@ maven_jar(
     src_sha1 = "e0b973d5cafef3d145fa80cdf032fcead1186d29",
 )
 
-maven_jar(
-    name = "protobuf",
-    artifact = "com.google.protobuf:protobuf-java:3.0.0-beta-2",
-    sha1 = "de80fe047052445869b96f6def6baca7182c95af",
-)
-
 maven_jar(
     name = "joda-time",
     artifact = "joda-time:joda-time:2.9.4",

lib/BUILD

@@ -65,7 +65,7 @@ java_library(
     name = "protobuf",
     data = ["//lib:LICENSE-protobuf"],
     visibility = ["//visibility:public"],
-    exports = ["@protobuf//jar"],
+    exports = ["@com_google_protobuf//:protobuf_java"],
 )
 
 java_library(