Added "express --paas heroku" option which adds package.json entries for heroku deployment to work out-of-the-box

[curious-attempt-bunny]

I keep having to copy and paste the correct engines settings for package.json before deploying a new app to heroku. This pull request will make that easier. Simple code, although I may have over-thought the generality of the --paas switch.

----------------- Prior to this pull request the first deploy experience is as follows:

-----> Node.js app detected
-----> Resolving engine versions

   WARNING: No version of Node.js specified in package.json, see:
   https://devcenter.heroku.com/articles/nodejs-versions

   WARNING: The default version of Node.js and npm on Heroku will begin
   tracking the latest stable release starting September 1, 2012.

   Using Node.js version: 0.4.7
   Using npm version: 1.0.106

-----> Fetching Node.js binaries
-----> Vendoring node into slug
-----> Installing dependencies with npm
npm ERR! error installing express@3.0.6 Error: Unsupported
npm ERR! error installing express@3.0.6 at checkEngine (/tmp/node-npm-5DgI/lib/install.js:493:14)
npm ERR! error installing express@3.0.6 at Array.0 (/tmp/node-npm-5DgI/node_modules/slide/lib/bind-actor.js:15:8)
npm ERR! error installing express@3.0.6 at LOOP (/tmp/node-npm-5DgI/node_modules/slide/lib/chain.js:15:13)
npm ERR! error installing express@3.0.6 at chain (/tmp/node-npm-5DgI/node_modules/slide/lib/chain.js:20:4)
npm ERR! error installing express@3.0.6 at installOne_ (/tmp/node-npm-5DgI/lib/install.js:470:3)
npm ERR! error installing express@3.0.6 at installOne (/tmp/node-npm-5DgI/lib/install.js:411:3)
npm ERR! error installing express@3.0.6 at /tmp/node-npm-5DgI/lib/install.js:347:9
npm ERR! error installing express@3.0.6 at /tmp/node-npm-5DgI/node_modules/slide/lib/async-map.js:54:35
npm ERR! error installing express@3.0.6 at Array.forEach (native)
npm ERR! error installing express@3.0.6 at /tmp/node-npm-5DgI/node_modules/slide/lib/async-map.js:54:11
npm ERR! error rolling back express@3.0.6 Error: ENOTEMPTY, Directory not empty '/tmp/build_2tgwfkdt0s1k3/node_modules/express'
npm ERR! Unsupported
npm ERR! Not compatible with your version of node/npm: connect@2.7.2
npm ERR! Required: {"node":">= 0.5.0"}
npm ERR! Actual: {"npm":"1.0.106","node":"0.4.7"}

[curious-attempt-bunny]

// generate with heroku support
express -p
express --paas

// generates with heroku support
express -p heroku
express --paas heroku
express -p heroku path/to/my/app
express --paas heroku path/to/my/app

// fail to generate in surprising ways (they write to the current directory)
express -p path/to/my/app
express --paas path/to/my/app

This is because this line in bin/express consumes it:

var path = program.args.shift() || '.';

Thoughts?

[shesek]

I add the engines definition to non-Heroku projects too. Maybe a separate --engines instead? Or even just enable it by default? And perhaps it should add node/npm with the locally installed version, rather than hard-coding it?

Also, what about Procfile?

[curious-attempt-bunny]

@shesek Yes. --engines is a much better idea. I wasn't sure about non-heroku environments. I'll make that change.

The Procfile isn't necessary as heroku will pick up the start script from the package.json.

[curious-attempt-bunny]

I'm closing this pull request now that I've superseeded it with this pull request: #1486