Enhance gradle idea task

#143
Add run config customization for IntelliJ
Change license header (checkstyle warnings)
Merge pull request #150 from mkalb/license

Change license header (checkstyle warnings)
Update CHANGELOG.md

gradle update 1.8
Update CONTRIBUTING.md

Added some content (license and versioning)
Merge pull request #149 from Cervator/ide

Add run config customization for IntelliJ
Add new gradle task distChangelog

Copy CHANGELOG into distributions folder.
Needed for Jenkins and #131
Merge pull request #151 from mkalb/changelog

Add new gradle task distChangelog
Initial preparations for changes in The Great Convergence