add credential plugin system and minimal working hashivault

awx/main/management/commands/setup_managed_credential_types.py

@@ -0,0 +1,14 @@
+# Copyright (c) 2019 Ansible by Red Hat
+# All Rights Reserved.
+
+from django.core.management.base import BaseCommand
+
+from awx.main.models import CredentialType
+
+
+class Command(BaseCommand):
+
+    help = 'Load default managed credential types.'
+
+    def handle(self, *args, **options):
+        CredentialType.setup_tower_managed_defaults()