CVZ -> Library

Created the cvz library.
Used by cvzCore and hierarchyXmlBuilder.
thrift still not completed
[cvz] Thrift the library WIP

Thrift interface for the abstract cvz. Still to deal with inheritance.
[cvz] Thrifting & inheritance

Had to create 2 .thrift files. We should check possibility of describing
more than one service in a file.
[cvz] Better doc, extended the thrift methods
Merge branch 'master' of https://github.com/robotology/wysiwyd