Revert Mynewt version metadata

Signed-off-by: Fabio Utzig <utzig@apache.org>
diff --git a/version.yml b/version.yml
index 4e69e62..13e5152 100644
--- a/version.yml
+++ b/version.yml
@@ -19,4 +19,4 @@
 
 # Newt uses this file to determine the version of a checked out repo.
 # This should always be 0.0.0 in the master branch.
-repo.version: 1.3.1
+repo.version: 0.0.0