Fixed npm module exports

[sickOscar]

Hello, I just published a npm package of PAHO client beacause I need it as an npm dependency in one of my projects.

I propose to add a module.exports at the end of the file to make it work in suck way.

Thank you

[jpwsutton]

@sickDevelopers Thanks for this PR. Because of some slowness on my part, this was one of three PRs that all attempted to accomplish the same thing, so I've made a manual commit (522b48f) that should satisfy all three. Note all new work goes to the develop branch, so you will need to test with that until we are ready to do a service release. Thanks again!

Any future PRs that you put forward would be very welcome, but we have a few requirements before we can accept them:

• You must sign the Eclipse ECA and Sign-off your commits.
• The Travis CI build must be passing
• All PRs need to target the develop branch
• It looks like this commit has an erroneous file that doesn't belong in the repository (npm-debug.log), we wouldn't have been able to accept this commit until it was removed.

Thanks again!