Refactors into a library that can be used separately from the API

moves XRay classes to `p3k\XRay` namespace

* removes the HTTP classes from this project and uses p3k-http library instead
* reorganizes the XRay classes into a psr-4 compatible folder
* moves controller autoload into -dev in preparation for turning this into a library (#17)

closes #20

skip image alt text for now

closes #34

replaced example post, closes #30

closes #36

Grabs rel values from both HTTP headers and link tags and merges them together, and resolves any relative values. Also returns the final URL requested and the HTTP response.

they are part of the reposted object instead.

closes #27

closes #24

* closes #23
* major refactor of the methods for extracting properties to consolidate the logic
* hReview parsing is incomplete due to issues with the php-mf2 backcompat parsing. see https://github.com/indieweb/php-mf2/issues/107

closes #16

* closes #14
* updated readme with details of the response
* includes `url` and `code` in the response with the final URL after following redirects and the HTTP status code returned