Added Invoke-Build to Build Automation

Invoke-Build is yet another build and test automation tool implemented in
PowerShell. It was inspired by Psake (in the list), implemented differently,
and somewhat moved further: it is arguably easier to use and has more features.

> To stay on the list, projects should follow these quality standards:

* Generally useful to the community
    * Invoke-Build is not so popular as Psake but it does the same and more.
* Actively maintained
    * It is used by the author on daily basis in many projects, issues are resolved on the fly.
* Stable
    * Very much stable.
* Documented
    * The built-in help alone is much larger then the source code; plus wiki at the project site.
* Tests
    * A lot. Invoke-Build itself is used as the testing tool, tests are implemented as build tasks.