API ReactComponent

[aaronschachter]

DRY our React fetch networking calls into a helper API class, where we can set the relevant URL's, headers, timeouts (#823), catch/handle network errors (#923), etc.

Also can log any interesting networking errors to Crashlytics non-fatal zone 👀

[aaronschachter]

It might be sick to create our own SlothKit JS library for this, a la https://github.com/philschatz/octokat.js

cc @jonuy @DFurnes

[jonuy]