added travis testing

travis builds and spins up containers for sqlite, mariadb and postgres
and runs a simple python test script for accessing the wallabag.

tests/test_login.py

@@ -0,0 +1,14 @@
+import requests
+
+
+URL = 'http://127.0.0.1:80'
+
+
+def test_login_page():
+    r = requests.get(URL, allow_redirects=True)
+
+    assert r.status_code == 200
+    assert 'Login' in r.text
+    assert 'Password' in r.text
+    assert 'Register' in r.text
+    assert 'Username' in r.text