eclass: add devicejail user/group, cuse group

The cuse group will have access to /dev/cuse. We will
run device_jail and device_jail_fs as the device_jail
user in order to make sure we don't have root daemons
running around.

BUG=chromium:644338
TEST=build_packages, check /build/board

Change-Id: I6750ff0347d80558dc084ee30a5f227124496d24
Reviewed-on: https://chromium-review.googlesource.com/410061
Commit-Ready: Eric Caruso <ejcaruso@chromium.org>
Tested-by: Eric Caruso <ejcaruso@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
diff --git a/profiles/base/accounts/group/cuse b/profiles/base/accounts/group/cuse
new file mode 100644
index 0000000..4cf0ae2
--- /dev/null
+++ b/profiles/base/accounts/group/cuse
@@ -0,0 +1,3 @@
+group:cuse
+gid:606
+users:devicejail
diff --git a/profiles/base/accounts/group/devicejail b/profiles/base/accounts/group/devicejail
new file mode 100644
index 0000000..e20bcdd
--- /dev/null
+++ b/profiles/base/accounts/group/devicejail
@@ -0,0 +1,3 @@
+group:devicejail
+gid:283
+users:
diff --git a/profiles/base/accounts/user/devicejail b/profiles/base/accounts/user/devicejail
new file mode 100644
index 0000000..7dba4af
--- /dev/null
+++ b/profiles/base/accounts/user/devicejail
@@ -0,0 +1,6 @@
+user:devicejail
+uid:283
+gid:283
+gecos:device sandbox user
+home:/dev/null
+shell:/bin/false