Fix loopback service status

Currently when Salt starts setup-loopback-device service
systemd executes losetup command and even if it worked
successfully, systemd marks service as inactive(dead).
And Salt considers service as dead. In order to fix
this behavior, we need to add RemainAfterExit=true to
loopback systemd unit template.

Other changes:
.gitreview added

Related Prod: https://mirantis.jira.com/browse/PROD-11760

Change-Id: I6d0c3baf1c22d0a626ff1fd6aaab802c08fb029e
diff --git a/.gitreview b/.gitreview
new file mode 100644
index 0000000..8799235
--- /dev/null
+++ b/.gitreview
@@ -0,0 +1,5 @@
+[gerrit]
+host=gerrit.mcp.mirantis.net
+port=29418
+project=salt-formulas/linux
+