Adjust to upstream buck and new bucklet version

Java 7 is default now. java7.bucklet was therefore removed.

Change-Id: I3e2455b02c35a663ac6c4638e60d4de2bbae2c95

.buckversion

diff --git a/.buckversion b/.buckversion
index ea13b51..cec726d 100644
--- a/.buckversion
+++ b/.buckversion
@@ -1 +1 @@
-ca48f0fff22f7fbcb856fd2faa6e15e7de900775
+1ba4496a782b40dec33a42e69a74837afee06177