build: Remove type init option for gtk-doc

We're building against a required version of GLib that does not need
type initialization.
build: Remove bogus rules

We don't need check targets any more.
build: Add missing file

We need to dist the tap-test script.
Release JSON-GLib 0.99.2 (1.0.0-rc1)

First release candidate for JSON-GLib.
Post-release version bump to 0.99.3