Update metadata in setup.py to reflect new licence and minimum Python version. Update R-package licence to Apache 2 to match Python package

Author: Szubie

R-package/DESCRIPTION

@@ -12,7 +12,7 @@ Description: Implementation of the ivis algorithm as described in the paper:
   with neighbouring points being pulled together and non-neighours being pushed away.
 Depends: R (>= 3.2.3)
 Imports: reticulate
-License: MIT 
+License: Apache License, Version 2.0
 Encoding: UTF-8
 LazyData: true
 RoxygenNote: 7.0.2

setup.py

@@ -17,8 +17,9 @@
       url='http://github.com/beringresearch/ivis',
       author='Benjamin Szubert, Ignat Drozdov',
       author_email='bszubert@beringresearch.com, idrozdov@beringresearch.com',
-      license='GNU General Public License v2.0',
+      license='Apache License, Version 2.0',
       packages=find_packages(),
+      python_requires='>=3.5',
       install_requires=[
           'numpy',
           'scikit-learn>0.20.0',