Add support for Python 3.8. (#286)

* Add support for Python 3.8.

modified:   .travis.yml
modified:   CHANGES.rst
modified:   setup.py
modified:   tox.ini
modified:   appveyor.yml

.travis.yml

 language: python
-dist: xenial
 python:
   - 2.7
   - 3.5
   - 3.6
   - 3.7
+  - 3.8
   - pypy
   - pypy3
 

CHANGES.rst

@@ -13,6 +13,8 @@
 
 - Drop support for Python 3.4.
 
+- Add support for Python 3.8.
+
 - Fix ``DB.undo()`` and ``DB.undoMultiple()`` to close the storage
   they open behind the scenes when the transaction is committed or
   rolled back. See `issue 268

appveyor.yml

@@ -8,6 +8,8 @@ environment:
     - python: 36-x64
     - python: 37
     - python: 37-x64
+    - python: 38
+    - python: 38-x64
 
 install:
   - "SET PATH=C:\\Python%PYTHON%;c:\\Python%PYTHON%\\scripts;%PATH%"

setup.py

@@ -25,6 +25,7 @@ Programming Language :: Python :: 3
 Programming Language :: Python :: 3.5
 Programming Language :: Python :: 3.6
 Programming Language :: Python :: 3.7
+Programming Language :: Python :: 3.8
 Programming Language :: Python :: Implementation :: CPython
 Programming Language :: Python :: Implementation :: PyPy
 Topic :: Database

tox.ini

 [tox]
-# Jython 2.7rc2 does work, but unfortunately has an issue running
-# with Tox 1.9.2 (http://bugs.jython.org/issue2325)
-#envlist = py26,py27,py33,py34,pypy,simple,jython,pypy3
-envlist = py27,py35,py36,py37,pypy,pypy3
+envlist = py27,py35,py36,py37,py38,pypy,pypy3
 
 [testenv]
 # ZODB.tests.testdocumentation needs to find