Added workspace tag hierarchy
Merge branch 'master' of https://github.com/claroline/Claroline

Conflicts:
	src/core/Claroline/CoreBundle/Controller/WorkspaceController.php
	src/core/Claroline/CoreBundle/Controller/WorkspaceTagController.php
fixed merge issue + checkstyle
Merge branch 'master' of https://github.com/claroline/Claroline