Revert BaseTools: PYTHON3 migration

This reverts commit 6693f359b3c213513c5096a06c6f67244a44dc52..
678f851312.

Python3 migration is the fundamental change. It requires every developer
to install Python3. Before this migration, the well communication and wide
verification must be done. But now, most people is not aware of this change,
and not try it. So, Python3 migration is reverted and be moved to edk2-staging
Python3 branch for the edk2 user evaluation.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Liming Gao <liming.gao@intel.com>

BaseTools/Source/Python/Common/LongFilePathSupport.py

@@ -1,7 +1,7 @@
 ## @file
 # Override built in function file.open to provide support for long file path
 #
-# Copyright (c) 2014 - 2018, Intel Corporation. All rights reserved.<BR>
+# Copyright (c) 2014 - 2015, Intel Corporation. All rights reserved.<BR>
 # This program and the accompanying materials
 # are licensed and made available under the terms and conditions of the BSD License
 # which accompanies this distribution.  The full text of the license may be found at
@@ -49,3 +49,15 @@ def CopyLongFilePath(src, dst):
     with open(LongFilePath(src), 'rb') as fsrc:
         with open(LongFilePath(dst), 'wb') as fdst:
             shutil.copyfileobj(fsrc, fdst)
+
+## Convert a python unicode string to a normal string
+#
+# Convert a python unicode string to a normal string
+# UniToStr(u'I am a string') is 'I am a string'
+#
+# @param Uni:  The python unicode string
+#
+# @retval:     The formatted normal string
+#
+def UniToStr(Uni):
+    return repr(Uni)[2:-1]