Import fixed release script from mainline commit 5df7894805aad5487afdd5d3b1f840fff19f1a60.
Set release branch version to 0.4.0-rc2.
Fix EzRpc example.
Add a sample RPC application, and fix some bugs / add some missing features needed by said app.

Conflicts:
	mega-test.cfg
Oops, regenerate bootstraps.
Hack to make it safe to read capabilities from default values (returning broken caps) without introducing a dependency from libcapnp on libcapnp-rpc.