ceph-volume: create a utf-8 string decoder for py3 compat

Signed-off-by: Alfredo Deza <adeza@redhat.com>

src/ceph-volume/ceph_volume/util/__init__.py

@@ -0,0 +1,10 @@
+
+def as_string(string):
+    """
+    Ensure that whatever type of string is incoming, it is returned as an
+    actual string, versus 'bytes' which Python 3 likes to use.
+    """
+    if isinstance(string, bytes):
+        # we really ignore here if we can't properly decode with utf-8
+        return string.decode('utf-8', 'ignore')
+    return string