[Fixed] comment
[Fixed] metadata key value extraction in REST (FS \ Data) endpoints
[Changed] reverting metadata decoding code back
[Added] FS cleanup manager is introduced: it should help to cleanup a detached FS part after fs part root(directory) is marked to be deleted
[Added] BFS tree traversal helper and FS tree bfs traversal implementation - to help effectively traverse detached fs tree and delete it's nodes
[Fixe] FS manager canBeDeleted check is fixed for root directories case
[Fixed] match error exception is fixed for non-empty directories deletion
Merge remote-tracking branch 'origin/recursive_dir_removal' into recursive_dir_removal

Conflicts:
	c3-platform/c3-filesystem/src/main/scala/org/aphreet/c3/platform/filesystem/impl/FSManagerImpl.scala