CHANGELOG for 2.1

This changelog references the relevant changes (bug and security fixes) done in 2.1 minor versions.

feature #67 - move all github files inside .github folder
feature #66 - add missing licence
feature #62 - add additional filter component
feature #71 - add new Objects\Value component to wrap additional filter's value
fix #68 - add GraphWalker to create mocks for testing purpose