Fix setup.py to include headers and move to setuptools

This will allow to create tag.gz source package by running:
python setup.py sdist
and create wheel package by running:
pip install wheel
python setup.py bdist_wheel

MANIFEST.in

@@ -0,0 +1,9 @@
+# file GENERATED by distutils, do NOT edit
+include setup.py
+include lm/*.cc
+include lm/*.hh
+include python/*.cpp
+include util/*.cc
+include util/*.hh
+include util/double-conversion/*.cc
+include util/double-conversion/*.h

setup.py

@@ -1,5 +1,4 @@
-from distutils.core import setup
-from distutils.extension import Extension
+from setuptools import setup, Extension
 import glob
 import platform
 import os
@@ -44,5 +43,6 @@ def compile_test(header, library):
 
 setup(
     name='kenlm',
-    ext_modules=ext_modules
+    ext_modules=ext_modules,
+    include_package_data=True,
 )