Support new gasket.json format for types, added types fork, background, map, reduce, and updated README

[melaniecebula]

NOTE: Planning to add support for nested commands in another PR

Following mafintosh's proposed plan here, which I really like: https://gist.github.com/mafintosh/352f84dc924e0c404e99

• Changed gasket format (object with .command and .type) to support different types and nesting later on
• Treat commands as streams
• Added fork, backgrounds, map, and reduce in addition to pre-existing pipe/run commands
• Updated README to include other command-types and how to use them

Feedback appreciated!

[okdistribute]

this looks great. i was looking around for tests and didn't find any :O it might be a good idea to have them at some point

[melaniecebula]

Yes, tests would be great. (That way I could know if I broke things .. :P)

[mafintosh]

Instead of piping background streams directly to stdout you should join them with the main pipeline using a parallel-multistream before returning.

if (bkgds.length) {
  return parallel(mainPipeline, bkgds)
} else {
  return mainPipeline
}

That means you (the user) can pipe it anywhere you want! :)

[mafintosh]

@karissa the lack of tests are my fault - we should definitely add some soon :) @melaniecebula other than my comments this looks great!

we should probably rebase this to a single (or a few) commit as well

[melaniecebula]

Awesome! I'll be incorporating your guy's feedback and update the PR later today!

[mafintosh]

:+1: LGTM from me

[mafintosh]

@melaniecebula i've added you as owner on the npm module as well so you can have the honor of releasing this :)