Add Python 3.7 and 3.8

Author: hugovk

setup.py

@@ -42,12 +42,16 @@
         'Operating System :: Microsoft :: Windows',
         'Operating System :: POSIX :: Linux',
         'Programming Language :: Python',
+        'Programming Language :: Python :: 2',
         'Programming Language :: Python :: 2.6',
         'Programming Language :: Python :: 2.7',
+        'Programming Language :: Python :: 3',
         'Programming Language :: Python :: 3.3',
         'Programming Language :: Python :: 3.4',
         'Programming Language :: Python :: 3.5',
         'Programming Language :: Python :: 3.6',
+        'Programming Language :: Python :: 3.7',
+        'Programming Language :: Python :: 3.8',
         'Topic :: Scientific/Engineering :: Bio-Informatics',
     ],
     python_requires='>=2.6, !=3.0.*, !=3.1.*, !=3.2.*',