Move example app into separate repo or subdirectory

[darinwilson]

I'd like to propose switching torch from being structured as an umbrella app, to either having the example app in a separate repo, or pushing it down into a separate subdirectory (like we're doing with thesis-phoenix.

The biggest bummer about the current arrangement is that it's impossible to set up the torch dependency to point to your own git branch because the dependency format in mix.exs does not support pointing to a subdirectory (AFAIK). This means you can only use the current official hex package, or a repo on your local filesystem. Pointing your deps at github branches is not ideal, but it's a necessary evil, particularly in these early stages.

I'm open to other possibilities, but the current setup is a little clumsy when developing new features.

[darinwilson]

Closed by #33