Update config files for setup and github

Author: RJMW

.travis.yml

@@ -1,7 +1,10 @@
+dist: xenial
 language: python
 python:
-  - "2.7"
-  - "3.6"
+  - "3.7"
+
+services:
+  - xvfb
 
 install:
   - pip install coverage
@@ -10,8 +13,6 @@ install:
 
 before_script:
   - "export DISPLAY=:99.0"
-  - "sh -e /etc/init.d/xvfb start"
-  - sleep 3 # give xvfb some time to start
 
 script:
   - beams --help

appveyor.yml

@@ -1,7 +1,6 @@
 environment:
   matrix:
-    - PYTHON: "C:\\Python27"
-    - PYTHON: "C:\\Python36"
+    - PYTHON: "C:\\Python37"
 
 build_script:
   - '%PYTHON%\python.exe -m pip install .'

setup.py

@@ -24,10 +24,9 @@ def main():
         install_requires=install_requires,
         include_package_data=True,
         classifiers=[
-            "Programming Language :: Python :: 2",
-            "Programming Language :: Python :: 2.7",
             "Programming Language :: Python :: 3",
             "Programming Language :: Python :: 3.6",
+            "Programming Language :: Python :: 3.7",
             "Topic :: Scientific/Engineering :: Bio-Informatics",
             "Topic :: Scientific/Engineering :: Chemistry",
             "Topic :: Utilities",