#394 Migrate from Maven to Gradle

[Marcin Erdmann]

This will make it much easier to build the project (thanks to Gradle wrapper ony machine with java installed will be able to build the project without any aditional setup) and setup it in IDEs (using gradle eclipse and idea plugins).

Use Gradle Site plugin from Rene Gröschke: https://github.com/breskeby/GradleSite

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