Jaeger exporter require wrapper does not play nicely with Webpack

[tstirrat15]

Please answer these questions before submitting a bug report.

What version of OpenCensus are you using?

Master branch.

What version of Node are you using?

Node 8

What did you do?

Our project bundles both frontend and backend code using Webpack. This means that while this code is fine on Node, Webpack has no idea what to do with it, because it uses an internal require wrapper that doesn't work in this context.

What did you expect to see?

That this code can be bundled just fine using webpack.

What did you see instead?

I get a runtime error:

path.js:28
    throw new TypeError('Path must be a string. Received ' + inspect(path));
    ^

TypeError: Path must be a string. Received 1122
    at assertPath (path.js:28:11)
    at Object.dirname (path.js:1346:5)
    at Object.<anonymous> (/home/me/project/build/server.js:72478:24)
    at __webpack_require__ (/home/me/project/build/server.js:27:30)
    at Object.module.exports.Object.defineProperty.value (/home/me/project/build/server.js:72297:25)
    at __webpack_require__ (/home/me/project/build/server.js:27:30)
    at Object.<anonymous> (/home/me/project/build/server.js:43500:10)
    at __webpack_require__ (/home/me/project/build/server.js:27:30)
    at Module.<anonymous> (/home/me/project/build/server.js:67332:85)
    at Module.module.exports.m (/home/me/project/build/server.js:67452:30)

[tstirrat15]

This was closed by #302.