drop python 2

bin/haruhi-dl

@@ -1,6 +1,10 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
-import haruhi_dl
+import sys
 
 if __name__ == '__main__':
-    haruhi_dl.main()
+    if sys.version_info[0] == 2:
+        sys.exit('haruhi-dl no longer works on Python 2, use Python 3 instead')
+    else:
+        import haruhi_dl
+        haruhi_dl.main()