Security Issues binding to all interfaces

[stevensmi]

Thanks for a great tool. Normally I test Email function internally (localhost). Mailsnag listens on all interfaces. This exposes the code to any malicus system on the local network. Not a big risk but not great. I would like to extend Mailsnag so by default it only binds to localhost. I can look into creating a patch for this if you require.

[foosbar]

Sounds like a nice feature. I'll take a look once you submit a pull request!