Flask app fails - seems to have not installed the pips

Hi TJ! This seems like a pretty cool project and as a Go fan I think I'd prefer it to Serverless. Let me know if I can help!

Thanks,
Daniel

```
❯❯❯ up url | xargs curl ~/P/u/o/python-flask (master)
{"message": "Internal server error"}⏎
```

```
❯❯❯ up logs -f ~/P/u/o/python-flask (master)
7:00:04am INFO starting name: app type: server
7:00:04am INFO found free port 37847 version: $LATEST
7:00:04am INFO executing "FLASK_APP=app.py python -m flask run -p $PORT" version: $LATEST
7:00:04am INFO waiting for http://127.0.0.1:37847 (timeout 5s) version: $LATEST
7:00:04am ERRO /usr/bin/python: No module named flask
7:00:09am FATA error: initializing relay: waiting for http://127.0.0.1:37847 to be in listening state: timed out after 5s
7:00:10am INFO starting name: app type: server
7:00:10am INFO found free port 36095 version: $LATEST
```

```
❯❯❯ up version ~/P/u/o/python-flask (master)
0.2.3
```

```
❯❯❯ git log ~/P/u/o/python-flask (master)
commit f524a2334358dfe19b3029aa8ba129636dd022b1 (HEAD -> master, origin/master, origin/HEAD)
Author: TJ Holowaychuk
Date: Tue Sep 12 12:42:27 2017 -0700

tweak a description
```