Update Soy to latest upstream release

Change-Id: I441aab53395c615d4d61938a87d966c3a5ba4b79

lib/soy/BUCK

diff --git a/lib/soy/BUCK b/lib/soy/BUCK
index 21fbd94..dbd5aac 100644
--- a/lib/soy/BUCK
+++ b/lib/soy/BUCK
@@ -1,12 +1,11 @@
 maven_jar(
   name = 'soy',
-  id = 'com.google.template:soy:e74fcfa284a1e31d42ac93e53cb84a71f638c70b',
-  sha1 = '1c75a007218f29d6124c46c8b18f4158cba4839c',
+  id = 'com.google.template:soy:2015-04-10',
+  sha1 = 'f2a260c0eafbc5756ccec546efd2ffd5b0a583cb',
   deps = [
     ':icu4j',
     '//lib:jsr305',
   ],
-  repository = GERRIT,
 )
 
 maven_jar(