Allow for reproducible builds

REPRODUCIBLE_BUILD=1 ./gradlew clean :build

gradle/reprod/patches/mixingradle/0001-Configure-gradle-to-build-reproducible-archives.patch

@@ -0,0 +1,28 @@
+From 34446d49be65c3a17e962c2e4053ed3e41aa2ab4 Mon Sep 17 00:00:00 2001
+From: Jonas Herzig <me@johni0702.de>
+Date: Mon, 7 Aug 2017 20:04:25 +0200
+Subject: [PATCH 1/3] Configure gradle to build reproducible archives
+
+---
+ build.gradle | 5 +++++
+ 1 file changed, 5 insertions(+)
+
+diff --git a/build.gradle b/build.gradle
+index 3127c7f..c34a8a2 100644
+--- a/build.gradle
++++ b/build.gradle
+@@ -71,6 +71,11 @@ task groovydocJar(type: Jar, dependsOn: groovydoc) {
+     classifier = 'groovydoc'
+ }
+ 
++tasks.withType(AbstractArchiveTask) {
++    preserveFileTimestamps = false
++    reproducibleFileOrder = true
++}
++
+ artifacts {
+     archives jar
+     archives groovydocJar
+-- 
+2.5.5
+