Suggestion: Remove dev dependency on global packages

[spicywhitefish]

In package.json:
`- "postinstall": "typings install",

• "test": "gulp test"
• "gulp": "node node_modules/.bin/gulp",
• "typings": "node node_modules/.bin/typings",
• "test": "npm run gulp test",
• "postinstall": "npm run typings -- install"`

Now gulp install (global gulp) is npm run gulp install.
This approach, while a little more verbose, is more accommodating for users or CI environments with a different version of typings or gulp installed globally.

[spicywhitefish]

Closing this issue, as this approach has caused difficulties for cross-platform dev. Specifically, the files in node_modules/.bin for Windows are bash scripts, but on OS X, they are JavaScript.