Merge branch 'stable-2.16' into stable-3.0

* stable-2.16:
  Bazel: Mark truth libraries as test only
  Bump Bazel version to 2.0.0

Change-Id: I00beceb92d9a6bcb1a9826d348d01dd5cea42237

lib/truth/BUILD

diff --git a/lib/truth/BUILD b/lib/truth/BUILD
index bb30945..dc1d802 100644
--- a/lib/truth/BUILD
+++ b/lib/truth/BUILD
@@ -2,6 +2,7 @@
 
 java_library(
     name = "truth",
+    testonly = True,
     data = ["//lib:LICENSE-DO_NOT_DISTRIBUTE"],
     visibility = ["//visibility:public"],
     exports = ["@truth//jar"],
@@ -14,6 +15,7 @@
 
 java_library(
     name = "truth-java8-extension",
+    testonly = True,
     data = ["//lib:LICENSE-DO_NOT_DISTRIBUTE"],
     visibility = ["//visibility:public"],
     exports = ["@truth-java8-extension//jar"],
@@ -25,6 +27,7 @@
 
 java_library(
     name = "truth-liteproto-extension",
+    testonly = True,
     data = ["//lib:LICENSE-DO_NOT_DISTRIBUTE"],
     visibility = ["//visibility:private"],
     exports = ["@truth-liteproto-extension//jar"],
@@ -37,6 +40,7 @@
 
 java_library(
     name = "diffutils",
+    testonly = True,
     data = ["//lib:LICENSE-DO_NOT_DISTRIBUTE"],
     visibility = ["//visibility:private"],
     exports = ["@diffutils//jar"],
@@ -44,6 +48,7 @@
 
 java_library(
     name = "truth-proto-extension",
+    testonly = True,
     data = ["//lib:LICENSE-DO_NOT_DISTRIBUTE"],
     visibility = ["//visibility:public"],
     exports = [