Provide dockerfile for builds

[jdbohrman]

Per #33 I think it would be prudent to provide a dockerfile to containerize the app and allow for smoother testing and deployment. See https://docs.travis-ci.com/user/docker/ for reference.

[asb-capfan]

I have to admit, I don't see the benefit of creating a dockerfile for this Perl module.
Tests are easily done by forging input and expecting output. After all, that's "all" what the module does.
The deployment is user-specific anyway and there is no safe way to cover all DataTables scenarios that could exists (just have a look at all the examples here: https://datatables.net/examples/index).

It sounds like a lot of work with little to no effect.
However, if somebody else does the work - why not.

[srchulo]

@jdbohrman , could you explain what you think that would offer?