AC-1071 Moved credential model to its own file. Added API support and tests for ssh_key_path field.

AC-1095 Added validation for SSH private keys.

awx/main/models/__init__.py

@@ -8,6 +8,7 @@ from django.conf import settings
 from awx.main.models.base import *
 from awx.main.models.unified_jobs import *
 from awx.main.models.organization import *
+from awx.main.models.credential import *
 from awx.main.models.projects import *
 from awx.main.models.inventory import *
 from awx.main.models.jobs import *