Implement colored output support for Tooling API and fix GRADLE-2687 (disable output to System.out/System.err when using Tooling API)

This PR includes 3 different changes:
- fix for [GRADLE-2687](https://issues.gradle.org/browse/GRADLE-2687) (I haven't tested the fix, so it might not be a complete fix.)
- force ANSI output in cli with -Dorg.gradle.ansi=true system property (disables any console detection)
- adds "setColorOutput(boolean colorOutput)" to LongRunningOperation interface in Tooling API and add implementation for that 
 - forces ANSI colored output to OutputStream provided with LongRunningOperation.setStandardOutput .
 - [Tooling API in color discussion on gradle-dev](http://gradle.1045684.n5.nabble.com/Tooling-API-in-color-td5712974.html)

This PR is incomplete and lacks tests. Please provide guidance about how to continue. You are free to take over anything in this PR. 
I'd just like to help getting these features to a stable Gradle version ASAP, since we'd like to use these features in the Grails 3 Gradle integration (uses Tooling API). 
I'm a total newbie to Gradle source code, so my changes might be the wrong way to solve the problem. 
However I tested manually that I got colored output from the Tooling API after these changes.

Regards,

Lari from the Grails team