u2f: Add u2f user to u2f group

As part of u2f daemon-store setup.

BUG=b:112603199, b:112603199
TEST=local test on soraka

Change-Id: I23eaaea38735eb84e8c58a250dc117e2938cc9ae
Reviewed-on: https://chromium-review.googlesource.com/1535467
Commit-Ready: Louis Collard <louiscollard@chromium.org>
Tested-by: Louis Collard <louiscollard@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
diff --git a/profiles/base/accounts/group/u2f b/profiles/base/accounts/group/u2f
index 63df187..895e331 100644
--- a/profiles/base/accounts/group/u2f
+++ b/profiles/base/accounts/group/u2f
@@ -1,3 +1,3 @@
 group:u2f
 gid:291
-users:
+users:u2f