Making the shell embeddable

[Xion]

I have slightly altered the setup file and runner script in order to make the HttpShell embeddable into other applications, like this:

from httpshell import repl

def run_httpshell(port=5000):
    server = 'localhost:%s' % port
    repl.main([server])

This makes it possible to integrate the shell as an option in management scripts for web apps, for example those created using Flask-Script. Of course, it is still possible to run the shell through $ httpsh localhost:5000.