Windows has some peculiarities for example it only allows one hostname per line
and the file's location depends on an environment variable. Although in most
cases just using C:\Windows\ for %WinDir% would probably work.
Note that editing the hosts file on Windows will require running with elevated
privileges ("Run as Administrator") and in some cases also antivirus may block
access to the file.
Introduces `--hosts-path [PATH]` and `--no-write-hosts` options in `innernet`.
This could be further improved to have a persistent setting in a config file i.e. /etc/innernet.conf (which doesn't currently exist).
Fixes#6
