Add user aiy to group i2c

* This will allow non-root i2c-dev access.

Change-Id: Iefcc72842fcf4deb49d72be3e84ecf289401b05c
diff --git a/debian/postinst b/debian/postinst
index 2df2b1a..2c2418a 100755
--- a/debian/postinst
+++ b/debian/postinst
@@ -22,7 +22,7 @@
 chown aiy:aiy /home/aiy
 echo 'aiy:aiy' |chpasswd
 
-GROUPS="adm audio bluetooth games input plugdev staff sudo users video netdev systemd-journal"
+GROUPS="adm audio bluetooth games i2c input plugdev staff sudo users video netdev systemd-journal"
 
 for group in $GROUPS; do \
 	adduser aiy $group; \