Feature: Add a helper to authenticate the request with BasicAuth

We'll be doing this in a bunch of different apps all with the same
implementation so it makes sense to put it in our helper gem.

I added an `AuthenticationHelper` class which contains an
`authenticate_with_basic_auth` method.

This requires that Chamber is installed and has a valid BasicAuth configuration
loaded in order to use this method.

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Change-Id:     I8177f2d7b0954287c1cbbca0077d7bd855aea093
Signed-off-by: Jeff Felchner <accounts+git@thekompanee.com>