jenkins: Add dist target

This will allow our build system to generate zip files containing the flashable
images. This requires a depdency on zip as well for the docker container.

Change-Id: Iaf700e11e8ee57d5d566002910829127b03e6cc2
diff --git a/Makefile b/Makefile
index 52a17df..ae394cc 100644
--- a/Makefile
+++ b/Makefile
@@ -51,6 +51,8 @@
 
 all: rootfs home bootloader partition-table
 
+dist: package-images sign-images
+
 lintian: packages
 	lintian $(PRODUCT_OUT)/packages/core/*.deb $(PRODUCT_OUT)/packages/bsp/*.deb
 
@@ -72,6 +74,7 @@
 include $(ROOTDIR)/build/multistrap.mk
 
 include $(ROOTDIR)/board/bootloader.mk
+include $(ROOTDIR)/board/dist.mk
 -include $(ROOTDIR)/board/sdcard.mk
 -include $(ROOTDIR)/board/flashcard.mk
 -include $(ROOTDIR)/board/recovery.mk
diff --git a/prereqs.mk b/prereqs.mk
index fb1488f..364a64b 100644
--- a/prereqs.mk
+++ b/prereqs.mk
@@ -62,6 +62,7 @@
 	rsync \
 	xz-utils \
 	wget \
+	zip \
 	zlib1g-dev
 
 prereqs: