Mutable File System

[matthewnanas]

Library should support read/write to Mutable File System (MFS) on Node similar to extension

1. Create folder/directory if it does not exist otherwise return none
2. Add ability to pin to MFS

[matthewnanas]

@SethDocherty When you get the time, feel free to take a look at d49ad49, creating folder(s) will exist within the Web3 class. Copying an asset to MFS will live in the Asset class through copy_to_mfs

[SethDocherty]

Details in this issue inspired some of the additions to the library.

A user now has the option to add content to an MFS folder via the uploadToIPFS method with the mfs_path parameter.

Once content is added to MFS, it's discoverable via the files ls command. A feature we'll be adding is the ability to copy an existing DAG (either stored on your local node or IPFS network) to the MFS.