Rescue from connection refused errors and return the appropriate status code

[andrewhavens]

When the app that is being proxied is not running, the code currently returns an exception. This prevents the exception and returns the appropriate status code.

[waterlink]

@andrewhavens Great work here! How do you plan to test this feature?

[andrewhavens]

@waterlink hmm...I'm not sure. I can't remember exactly how it's triggered. Somewhere in Rack I think. I suppose we could mock the error. What do you think?

[waterlink]

@andrewhavens We could try to use webmock and raise the error inside of the stub_request block. It might do the trick.

Also, I have noticed that the error connection refused handling is in the method. It would totally do the trick. What do you think, is there a more suitable place to put this error handling in?