Enhancement functional completion

Adds several bits of missing functionality:
- Listing Vaults (Issue #29)
- Multi-block Deletion
- File deletion

This sets us up nicely for being able to clean up a vault (well, with exception of being able to delete multiple fails like we do blocks...but that's a minor issue in comparison to what is done here)

CLOSES: Issue #29 
No, setitem() equivalent would be:

```python
blocks.setitem(block.block_id, block)
```

Where this is simply:
```python
block.add(block)
```