Support for unix sockets

Problem

server.address configuration option should also support listening to unix socket files since this is very common in linux servers environments and useful for proxying the application without taking a system port. Very useful feature for shared servers.

Would be cool running something like:

streamlit run --server.address "unix:~/.streamlit.sock" whatever.py

And having it creating the sock file and listening on it.

Solution

Never played with tornado but I believe it has built in unix sockets support so this might be easy to implement. With a fast google I found: https://gist.github.com/superduper/5579037 So bind_unix_socket seems to be the function for it!

[akrolsmir]

#1802 has been merged!

[tvst]

LGTM