CLI put command

Hello,

This is in response to nla/doss/issues/10

Use it like:

```sh
$ doss put file1 file2 file3
ID	Filename	Size
1	/Users/hrowland/Desktop/files/IMG_1579.JPG	462994 B
2	/Users/hrowland/Desktop/files/flame robin.jpg	24712 B
3	/Users/hrowland/Desktop/files/mrc-dragon.pdf	32301 B
4	/Users/hrowland/Desktop/files/nla-1.jpeg	96567 B
Created 4 blobs.
```

And accompanying unit tests.