Add shill user to daemon-store group.

Shill needs to access network profile and log info in /home/root/<hash>,
which has group ownership by daemon-store but no access rights for
"other".

CQ-DEPEND=CL:1121050
BUG=chromium:649417
TEST=tested as part of larger shill debug CL

Change-Id: I0e473457e2ce11b96ca6612d548ed9267304a614
Reviewed-on: https://chromium-review.googlesource.com/1121047
Commit-Ready: Micah Morton <mortonm@chromium.org>
Tested-by: Micah Morton <mortonm@chromium.org>
Reviewed-by: Mattias Nissler <mnissler@chromium.org>
Reviewed-by: Ben Chan <benchan@chromium.org>
diff --git a/profiles/base/accounts/group/daemon-store b/profiles/base/accounts/group/daemon-store
index 444df0d..98b913c 100644
--- a/profiles/base/accounts/group/daemon-store
+++ b/profiles/base/accounts/group/daemon-store
@@ -1,3 +1,3 @@
 group:daemon-store
 gid:400
-users:biod,chaps,crosvm
+users:biod,chaps,crosvm,shill