Bump version to 1.0-rc0

Look out 1.0, here we come!

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

VERSION

diff --git a/VERSION b/VERSION
index e653127..c78227b 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.15.50
+0.15.90