travis, appveyor: Add Python 3.8 build

.travis.yml

@@ -17,6 +17,7 @@ env:
   - PYTHON_VERSION=3.5
   - PYTHON_VERSION=3.6
   - PYTHON_VERSION=3.7
+  - PYTHON_VERSION=3.8
 
 before_install:
 - wget https://github.com/mzwiessele/travis_scripts/raw/master/download_miniconda.sh

appveyor.yml

@@ -11,6 +11,8 @@ environment:
       MINICONDA: C:\Miniconda36-x64
     - PYTHON_VERSION: 3.7
       MINICONDA: C:\Miniconda36-x64
+    - PYTHON_VERSION: 3.8
+      MINICONDA: C:\Miniconda36-x64
 
 #configuration:
 #  - Debug

setup.py

@@ -185,6 +185,7 @@ setup(name = 'GPy',
                    'Programming Language :: Python :: 3.5',
                    'Programming Language :: Python :: 3.6',
                    'Programming Language :: Python :: 3.7',
+                   'Programming Language :: Python :: 3.8',
                    'Framework :: IPython',
                    'Intended Audience :: Science/Research',
                    'Intended Audience :: Developers',