New Tutorial: Working with files (non-MFS methods)

[terichadbourne]

Separating out into this new issue the request to build a new tutorial on working with files using the non-MFS commands. (Issue #91 will now be focused only on the MFS tutorial, which will be produced first, via WIP PR #200.)

This tutorial won't be produced until the non-MFS API supports blobs (which @hugomrdias is working on separately).

Here's a quick overview of what the non-MFS lesson structure might look like. See #91 for other conversation around related educational examples.

Teaches regular part of API for files on IPFS (not MFS)
This would be very similar in scope to: https://github.com/ipfs/js-ipfs/tree/master/examples/ipfs-101

• Introduce how to use @mikeal's new functionality to get files from your desktop to where they can be played with in ProtoSchool
• Introduce the file API - it uses the dag API (which we learned in previous lessons) under the hood but has lots of extra functionality built in to make it work with files. We could have done this on our own, but the file API saves us time.
• Add a file with node.add
• See how the CID is returned
• (Use the CID to view it on the gateway?)
• Using that same CID, use node.cat to retrieve the file
• Show how to add a file using wrapWithDirectory: true so that there will be a path (essentially a filename) and not just a hash returned
• Use node.get to retrieve the file and see both path and content (highlight differences between cat and get)

As we'll now be framing this as the more advanced file-related lesson, we may also need to make comparisons and reveal some of what was really happening behind the scenes in MFS.

[terichadbourne]

The non-MFS Files API now supports blobs as of v0.36.0 (release notes) and we just updated to 0.36.4 via #251, so it appears our blob blocker has been removed!