Add dependency on aiohttp

setup.py

@@ -38,6 +38,9 @@ setup(
         "beautifulsoup4>=4.5.0,<5.0",
         "wcwidth>=0.1.7",
         "urwid>=2.0.0,<3.0",
+        # TODO: test with aiohttp==3.7.0
+        "aiohttp>=3.7.0,<4.0",
+        "aiodns>=3.0.0,<4.0",
     ],
     entry_points={
         'console_scripts': [