Fix #1630 subdirectories not installed

During pip install the subdirectories are not mentioned for
setup.py. find_packages from setuptools now specifies them.
This problem appears for #1471 when install scholia with pip.

setup.py

@@ -1,5 +1,5 @@
 import os
-from setuptools import setup
+from setuptools import setup, find_packages
 import versioneer
 
 
@@ -15,7 +15,7 @@
     license='GPL',
     keywords='wikidata',
     url='https://github.com/WDscholia/scholia',
-    packages=['scholia'],
+    packages=find_packages(),
     package_data={
         "scholia": [
             "data/*",