Bump Bazel version to 2.0.0

Change-Id: I66dfa77b263f6500fc76a6dc0b6bf46065ea0019

.bazelversion

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