Fix Node module import issue

[ac-freeman]

See issue #2

[MateMalice]

Hi Andrew,

I agree that the fix you suggested is the cleanest, as there is only one export from index.js, so there is no need for a separate MailListener property of module.exports. (See my comments to Issues #2 and #7 )

Having said that, it is a breaking change that would affect others who have managed to import the module by using one of the methods mentioned in those issues (e.g. using ES6 destructuring).

As such, I will likely merge this after I've had a look at the various forks and NPM packages floating around with this functionality & given people some notice that this change is coming.

I will shortly fix the README though so that it reflects the correct way to import the package in the meantime.

Thanks

M