[ENH] Add PyTest + Travis

.travis.yml

@@ -4,6 +4,9 @@
   "install": [
     "pip install -r requirements.txt"
   ],
+  "script": [
+    "pytest"
+  ],
   "group": "stable",
   "dist": "trusty",
   "os": "linux"

test_gandi-ddns.py

+import gandi-ddns as script
+
+def test_get_ip():
+    assert script.get_ip() == 'test-toto'
\ No newline at end of file