Create transient config provider, temp dir logic

Allows us to have a new config provider for each setup, with no overlap
of the directories used, and automatic cleanup of those directories.

config_app/config_util/config/TransientDirectoryProvider.py

@@ -0,0 +1,30 @@
+import os
+from backports.tempfile import TemporaryDirectory
+
+from config_app.config_util.config.fileprovider import FileConfigProvider
+
+class TransientDirectoryProvider(FileConfigProvider):
+    """ Implementation of the config provider that reads and writes the data
+        from/to the file system, only using temporary directories,
+        deleting old dirs and creating new ones as requested.
+    """
+    def __init__(self, config_volume, yaml_filename, py_filename):
+        # Create a temp directory that will be cleaned up when we change the config path
+        # This should ensure we have no "pollution" of different configs:
+        # no uploaded config should ever affect subsequent config modifications/creations
+        temp_dir = TemporaryDirectory()
+        self.temp_dir = temp_dir
+        super(TransientDirectoryProvider, self).__init__(temp_dir.name, yaml_filename, py_filename)
+
+    def new_config_dir(self):
+        """
+        Update the path with a new temporary directory, deleting the old one in the process
+        """
+        temp_dir = TemporaryDirectory()
+
+        self.config_volume = temp_dir.name
+        self.temp_dir = temp_dir
+        self.yaml_path = os.path.join(temp_dir.name, self.yaml_filename)
+
+    def get_config_dir_path(self):
+        return self.config_volume