Defensive drivering.
Wait for PHP api instance to spin up when testing.
Trim down the build matrix a bit.

We probably only need one or two builds per minor version, except where there are BC breaks (e.g. 1.3.4).
Simplify build config.

It doesn't hurt if we set up the mongo driver, even if we're not testing the PHP backend.
Wait up to 2 seconds for the PHP api to spin up.