Bump Bazel version to 2.0.0

Change-Id: I9b9121b0c9e8f89f496593c74ff1740cf7c436fe

.bazelversion

diff --git a/.bazelversion b/.bazelversion
index 9084fa2..227cea2 100644
--- a/.bazelversion
+++ b/.bazelversion
@@ -1 +1 @@
-1.1.0
+2.0.0