chrony: bump version

And add hash file.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/chrony/chrony.hash

@@ -0,0 +1,3 @@
+# From http://listengine.tuxfamily.org/chrony.tuxfamily.org/chrony-announce/2014/09/msg00000.html
+md5	04ab702fc81150db06809562a9aaed92  chrony-1.31.tar.gz
+sha1	71bb46cad2f15760192795e60efdf23069973908  chrony-1.31.tar.gz

package/chrony/chrony.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-CHRONY_VERSION = 1.30
+CHRONY_VERSION = 1.31
 CHRONY_SITE = http://download.tuxfamily.org/chrony
 CHRONY_LICENSE = GPLv2
 CHRONY_LICENSE_FILES = COPYING