Add requests verify option in vault section

This fix allow pass requests 'verify' option from vault configs
If vault certificate signed with Intermediate CA,
and Intermedia CA sign by internal root CA,
requests will fail verifying vault certificate with error:

 _ssl.c:510: ... routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed

'verify' option allow explicitly specify ca-bundle, or disable verifications.
http://docs.python-requests.org/en/master/user/advanced/#ssl-cert-verification

salt/modules/vault.py

@@ -16,6 +16,7 @@ Functions to interact with Hashicorp Vault.
 
         vault:
             url: https://vault.service.domain:8200
+            verify: /etc/ssl/certs/ca-certificates.crt
             auth:
                 method: token
                 token: 11111111-2222-3333-4444-555555555555
@@ -27,6 +28,10 @@ Functions to interact with Hashicorp Vault.
     url
         Url to your Vault installation. Required.
 
+    verify
+        For details please see
+        http://docs.python-requests.org/en/master/user/advanced/#ssl-cert-verification
+
     auth
         Currently only token auth is supported. The token must be able to create
         tokens with the policies that should be assigned to minions. Required.

salt/runners/vault.py

@@ -56,8 +56,10 @@ def generate_token(minion_id, signature, impersonated_by_master=False):
                     'metadata': audit_data
                   }
 
+        verify = config.get('verify', None)
+
         log.trace('Sending token creation request to Vault')
-        response = requests.post(url, headers=headers, json=payload)
+        response = requests.post(url, headers=headers, json=payload, verify=verify)
 
         if response.status_code != 200:
             return {'error': response.reason}

salt/utils/vault.py

@@ -124,6 +124,9 @@ def make_request(method, resource, profile=None, **args):
     connection = _get_vault_connection()
     token, vault_url = connection['token'], connection['url']
 
+    if "verify" not in args:
+        args["verify"] = __opts__['vault'].get('verify', None)
+
     url = "{0}/{1}".format(vault_url, resource)
     headers = {'X-Vault-Token': token, 'Content-Type': 'application/json'}
     response = requests.request(method, url, headers=headers, **args)