Allow buffers to be given a name

[travisperson]

When doing ipfs.add we should allow buffers to be named.

ipfs.add([{name: 'filename.txt', data: new Buffer('file contents')}], function(...) {}

This will bring the supported input to

• Filename
• Raw buffer
• Named buffer

[travisperson]

Could also support named files (rename or put into subfolder)