Switch from pathlib to pathlib2

The pathlib backport module is no longer maintained. The development
has moved to the pathlib2 module instead.

Quoting from the pathlib's README:
"Attention: this backport module isn't maintained anymore. If you want
to report issues or contribute patches, please consider the pathlib2
project instead."

thefuck/conf.py

@@ -1,7 +1,10 @@
 from imp import load_source
 import os
 import sys
-from pathlib import Path
+try:
+    from pathlib import Path
+except ImportError:
+    from pathlib2 import Path
 from six import text_type
 from . import const
 

thefuck/corrector.py

@@ -1,4 +1,7 @@
-from pathlib import Path
+try:
+    from pathlib import Path
+except ImportError:
+    from pathlib2 import Path
 from .conf import settings
 from .types import Rule
 from . import logs

thefuck/utils.py

@@ -10,7 +10,10 @@ from decorator import decorator
 from difflib import get_close_matches
 from functools import wraps
 from inspect import getargspec
-from pathlib import Path
+try:
+    from pathlib import Path
+except ImportError:
+    from pathlib2 import Path
 from warnings import warn
 
 DEVNULL = open(os.devnull, 'w')