Merge branch 'stable-2.15' into stable-2.16

* stable-2.15:
  Bump bazel version to 1.0.0
  Upgrade bazlets to latest stable-2.15 to build with 2.15.17 API

Change-Id: I4a193b8372dd38e32206ef60631d62bf37a91960

.bazelversion

diff --git a/.bazelversion b/.bazelversion
index 25939d3..3eefcb9 100644
--- a/.bazelversion
+++ b/.bazelversion
@@ -1 +1 @@
-0.29.1
+1.0.0