Move PPA-API Repo into W3C Org Space and enable Echidna

[AramZS]

We are assigning this work to the W3C team to move the repo into the W3C GitHub Organization and activate the appropriate configuration following consensus being reached on #19

[AramZS]

@tjwhalen Let us know if you need anything else on this front.

[tjwhalen]

Majority of the repo transfer complete, with some outstanding tasks to finish so it's all working correctly (mainly Bikeshed things). It's now called "ppa" rather than "ppa-api", for consistency with naming conventions in other groups.