migrate session_ttl to be compatible with noc feature/config

tower/migrations/024_change_session_timeout.py

+# Third-party modules
+import yaml
+
+# Tower modules
+from tower.models.environment import Environment
+
+def migrate(migrator):
+    for env in Environment.select():
+        config = yaml.load(env.service_config)
+        if "session_ttl" in config[None]["login"]:
+            if "d" not in str(config[None]["login"]["session_ttl"]):
+                config[None]["login"]["session_ttl"] = str(config[None]["login"]["session_ttl"]) + "d"
+                env.service_config = yaml.dump(config)
+                env.save()
+