Retry Twisted web requests

This extends the excellent txretry by Terry Jones with error handling for common twisted.web.client errors and simple but opinionated functions to quickly get you started.

Example usage:

import treq
from txwebretry import retry3_exponential as retry3
from txwebretry import retry5_immediate as retry5

# Retry up to 3 times with exponential backoff
retry3(treq.get, 'http://localhost:8080/index.html')

# Retry up to 5 times without delay
retry5(treq.get, 'http://localhost:8080/index.html')