Tweaking ape.js to try to fix transaction callback error.

Fixes "Session transaction failed on Fireabse!"

The API must have changed or something, see https://www.firebase.com/docs/transactions.html

With this patch, the master will be able to connect to Firebase and start serving, and the client will be able to connect. However any changes on the master will blank out the body of the client, but I think that's an unrelated bug.