Removing unneeded from __future__ import statements.

Since we are on Python 3.6 and up, we don't need those anymore.

ebook_converter/ebooks/metadata/book/base.py

@@ -1,11 +1,3 @@
-#!/usr/bin/env python2
-# vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:ai
-from __future__ import absolute_import, division, print_function, unicode_literals
-
-__license__   = 'GPL v3'
-__copyright__ = '2010, Kovid Goyal <kovid@kovidgoyal.net>'
-__docformat__ = 'restructuredtext en'
-
 import copy, traceback
 
 from ebook_converter import prints
@@ -17,6 +9,11 @@ from ebook_converter.library.field_metadata import FieldMetadata
 from ebook_converter.utils.icu import sort_key
 from ebook_converter.polyglot.builtins import iteritems, unicode_type, filter, map
 
+
+__license__   = 'GPL v3'
+__copyright__ = '2010, Kovid Goyal <kovid@kovidgoyal.net>'
+__docformat__ = 'restructuredtext en'
+
 # Special sets used to optimize the performance of getting and setting
 # attributes on Metadata objects
 SIMPLE_GET = frozenset(STANDARD_METADATA_FIELDS - TOP_LEVEL_IDENTIFIERS)