JETRIS Version 1.2

This release includes the following changes:

• Add Launch4J configuration and a new Gradle taks launch4j for generating an Windows exe file
• Use a Gradle plugin to create MAC OS X app package and a dmg file
• Remove the publish HiScores functionality, as it did not work
• Remove the webapp source folder, since there is no web page anymore
• Small code improvements
• Update Gradle wrapper to version 2.5
• Update the documentation