Add '-loader' suffix to all Webpack loader references

[scottaddie]

Addresses issue #444 by explicitly adding a -loader suffix to all Webpack loader references.

[dnfclas]

Hi @scottaddie, I'm your friendly neighborhood .NET Foundation Pull Request Bot (You can call me DNFBOT). Thanks for your contribution!
You've already signed the contribution license agreement. Thanks!

The agreement was validated by .NET Foundation and real humans are currently evaluating your PR.

TTYL, DNFBOT;

[SteveSandersonMS]

Thanks for this @scottaddie!

Unfortunately it looks like the changes here are based on quite an old version of the JavaScriptServices code. For example, it still has the .dev.js/.prod.js files, which no longer exist in the latest code.

Would it be possible for you to make the changes based on the latest JavaScriptServices commit? The easiest way might be for you to close this PR and open a new one.

[scottaddie]

Oops! I was using the master branch instead of dev. I'll take care of it later today.