Include support to ca files for shacache

  ca file is required for work with Python>=2.7.9

slapcache/signature.py

@@ -66,11 +66,12 @@ class NetworkCache:
     self.dir_url = get_('upload-dir-url')
     self.cache_url = get_('upload-cache-url')
     self.signature_private_key_file = get_('signature_private_key_file')
+    self.shacache_ca_file = get_('shacache-ca-file')
     self.shacache_cert_file = get_('shacache-cert-file')
     self.shacache_key_file = get_('shacache-key-file')
     self.shadir_cert_file = get_('shadir-cert-file')
     self.shadir_key_file = get_('shadir-key-file')
-
+    self.shadir_ca_file = get_('shadir-ca-file')
 
     if network_cache_info.has_section('shacache'):
       self.directory_key = network_cache_info.get('shacache', 'key')
@@ -97,10 +98,13 @@ class NetworkCache:
     # convert '' into None in order to call nc nicely
     with NetworkcacheClient(self.cache_url, self.dir_url,
           signature_private_key_file=self.signature_private_key_file or None,
+          shacache_ca_file=self.shacache_ca_file or None,
           shacache_cert_file=self.shacache_cert_file or None,
           shacache_key_file=self.shacache_key_file or None,
           shadir_cert_file=self.shadir_cert_file or None,
           shadir_key_file=self.shadir_key_file or None,
+          shadir_ca_file=self.shadir_ca_file or None,
+
         ) as nc:
       return nc.upload(file_descriptor, key, **metadata_dict)