Merge pull request #40 from chdemko/master

Checkstyle, uml and test on ComparableSet
Update initiate-publish.sh
Check Style for Concept.java
Add unit tests for Concept.java (not 100%)
Update build.xml
Update ChangeLog
Merge pull request #41 from JeanFrancoisViaud/master

Concept
Update initiate-publish.sh
Implementing test equals
Modifying ChangeLog
Merge pull request #42 from chdemko/test-node

Implementing test equals
Add contribute page