checkin data is returned embedded like author data rather than in the `refs` object

closes #35

closes #40

thanks to the new backcompat in php-mf2 0.3.2

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