Create an OOP setup for providers

[tw2113]

Similar to #49

Get what we can from Gary at https://github.com/WebDevStudios/Automatic-Featured-Images-from-Videos/pull/54/files

With the realization that we can handle DailyMotion, I think it's time to revisit the idea of getting some classes and interfaces going for this.

We'd need to have a base non-branded class to handle finding URLs in general within the content length limit.

From that, read the first url found and determine which service it's from. From that, instantiate the branded class that handles the rest. The base extended class can also begin to handle all the parts of the upload process that don't need to know provider-specific details, and just needs the URL to handle.