Fix Issue-60: Replace encodestring and decodestring for standard_b64encode and standard_b64decode.

Author: dechristo

config/kube_config.py

@@ -105,7 +105,7 @@ def as_file(self):
                 else:
                     content = self._data
                 self._file = _create_temp_file_with_content(
-                    base64.decodestring(content))
+                    base64.standard_b64decode(content))
             else:
                 self._file = _create_temp_file_with_content(self._data)
         if self._file and not os.path.isfile(self._file):
@@ -120,7 +120,7 @@ def as_data(self):
             with open(self._file) as f:
                 if self._base64_file_content:
                     self._data = bytes.decode(
-                        base64.encodestring(str.encode(f.read())))
+                        base64.standard_b64encode(str.encode(f.read())))
                 else:
                     self._data = f.read()
         return self._data

config/kube_config_test.py

@@ -40,7 +40,7 @@
 
 
 def _base64(string):
-    return base64.encodestring(string.encode()).decode()
+    return base64.standard_b64encode(string.encode()).decode()
 
 
 def _format_expiry_datetime(dt):