Update the site readme.
Add promise.blockingMap() to make it easier to do transforms that require blocking.
Add support for Multicast Publisher to Streams
improve Spring java example to prevent initializing for each request
use Spring Boot 1.1.6.RELEASE version
Fix HttpClientSmokeSpec's use of a promise
Make MulticastPublisher reject new subscriptions when stream has signalled complete or error.

Javadoc updates
Another test case.
Use Gradle 2.1.
Merge pull request #439 from lhotari/spring-module-improve-1

Fix ratpack.spring.Spring javadoc's java example, upgrade to Spring Boot 1.1.6.RELEASE
Change throttle to buffer
Extract interface for Result type.
Allow stream subscription to be asynchronous.
Make the test more asynchronous.
Enhance the execution harness to allow detecting if the execution completed without returning the promised value or propagating the error.
Error if a promise is used more than once.

Closes #440.
Add mention of the exec harness for promises.
Publish metrics using Reactive-Streams support
Restructure the header handling to allow full use of pre-rendered headers to avoid garbage creation.
Test fixes.