Fix Travis build (Python 3.5+) (#67)

* use Python 3.5 on Travis

* bump Python requirement to 3.5+

.travis.yml

@@ -1,6 +1,6 @@
 language: python
 python:
-  - "3.4"
+  - "3.5"
 install:
   - pip install -r requirements.txt
   - pip install coveralls

setup.py

@@ -9,8 +9,8 @@
 from setuptools.command.test import test as TestCommand
 from setuptools import setup
 
-if sys.version_info < (3, 4, 0):
-    sys.stderr.write('FATAL: STUPS zign needs to be run with Python 3.4+\n')
+if sys.version_info < (3, 5, 0):
+    sys.stderr.write('FATAL: STUPS zign needs to be run with Python 3.5+\n')
     sys.exit(1)
 
 __location__ = os.path.join(os.getcwd(), os.path.dirname(inspect.getfile(inspect.currentframe())))
@@ -46,7 +46,10 @@ def read_version(package):
     'License :: OSI Approved :: Apache Software License',
     'Operating System :: POSIX :: Linux',
     'Programming Language :: Python',
-    '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',
     'Programming Language :: Python :: Implementation :: CPython',
 ]