add python 3.8, drop python 2 and 3.4

Closes: #1014

Signed-off-by: t0b3 <thomas.bettler@gmail.com>

.travis.yml

@@ -1,5 +1,4 @@
 # http://travis-ci.org/#!/RDFLib/rdflib
-sudo: false
 language: python
 branches:
   only:
@@ -10,16 +9,14 @@ git:
   depth: 3
 
 python:
-    - 2.7
-    - 3.4
     - 3.5
     - 3.6
+    - 3.7
 
-matrix:
+jobs:
   include:
-    - python: 3.7
+    - python: 3.8
       dist: xenial
-      sudo: true
 
 before_install:
     - pip install -U setuptools pip  # seems travis comes with a too old setuptools for html5lib

rdflib/extras/external_graph_libs.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python2.7
+#!/usr/bin/env
 # encoding: utf-8
 from __future__ import absolute_import
 from __future__ import division

setup.py

@@ -43,15 +43,14 @@ def find_version(filename):
     url="https://github.com/RDFLib/rdflib",
     license="BSD-3-Clause",
     platforms=["any"],
+    python_requires='>=3.5',
     classifiers=[
             "Programming Language :: Python",
-            "Programming Language :: Python :: 2",
             "Programming Language :: Python :: 3",
-            "Programming Language :: Python :: 2.7",
-            "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",
             "License :: OSI Approved :: BSD License",
             "Topic :: Software Development :: Libraries :: Python Modules",
             "Operating System :: OS Independent",

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 envlist =
-    py27,py34,py35,py36
+    py35,py36,py37,py38
 
 [testenv]
 setenv =
@@ -20,7 +20,7 @@ deps =
 
 [testenv:cover]
 basepython =
-    python2.7
+    python3.7
 commands =
     {envpython} run_tests.py --where=./ \
                  --with-coverage --cover-html --cover-html-dir=./coverage \