Add ability to set the user's shell, using a sane, per-platform default

Fix case insensitivity issue with platform included filenames

Change-Id: I434a89b2b0534c7883c35e4e5536346d41f90bf6
diff --git a/vars/RedHat.yml b/vars/RedHat.yml
new file mode 100644
index 0000000..c446aa0
--- /dev/null
+++ b/vars/RedHat.yml
@@ -0,0 +1,14 @@
+---
+# users vars/Redhat.yml
+#
+# SPDX-FileCopyrightText: © 2020 Open Networking Foundation <support@opennetworking.org>
+# SPDX-License-Identifier: Apache-2.0
+#
+# NOTE: Only put platform/OS-specific variables in this file.
+# Put all other variables in the 'defaults/main.yml' file.
+
+users_os_sudoers_group: "wheel"
+
+users_os_pw_type: "sha512crypt"
+
+users_default_shell: "/bin/bash"