Can't install with Yarn

[Rudloff]

Hello,

Because the postinstall script calls npm explicitely, the hangupsjs package can't be installed with Yarn:

yarn global v1.3.2
[1/4] Resolving packages...
warning hangupsjs > tough-cookie-filestore > tough-cookie@0.12.1: ReDoS vulnerability parsing Set-Cookie https://nodesecurity.io/advisories/130
[2/4] Fetching packages...
[3/4] Linking dependencies...
[4/4] Building fresh packages...
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error /home/pierre/.config/yarn/global/node_modules/hangupsjs: Command failed.
Exit code: 127
Command: npm run prepublish
Arguments: 

One solution would be to duplicate the command like this:

  "scripts": {
    "postinstall": "coffee -o lib src",
    "test": "mocha",
    "prepublish": "coffee -o lib src"
  },

Or you could use the yarn-or-npm package like this: yon run prepublish.