[release-notes] #79 Changelog in release notes separated by assigned labels
[release-notes] #79 Add support for custom header for Other improvements
[release-notes] #79 Minor improvements

 - Better support for nested sub lists in Markdown
 - Fix incompatibility with Java 7
 - Remove displaying category with 0 changes
 - Enhance displaying list with no changes at all
 - Support for "new feature" label