Enable peerDependencies in typings.json

[blakeembrey]

These dependencies act like devDependencies (E.g. install locally, don’t install when used as a dependency) but can be semantically separated for later logging, etc.

• Enabled additional flags for init
• Tidied up install and uninstall utils from fs

Closes typings/typings#203

[arlair]

Is this always on, or meant to be optionally configured in tsconfig.json?

I have a weird hack case that may not be worth considering because I am using an npm package, but not the peer dependencies. Currently Typings (0.6.10) checks for the peer dependencies existence and creating an error when they are not found.

See eldarlabs/cycle-ui#2

Previously I thought I had read Typings only installs types for the npm package and not any child dependencies, but this pull seems to suggest otherwise. If this peer dependency behaviour is opt in, it probably doesn't need to be doing this check.

[blakeembrey]

This is for peerDependencies in typings.json. package.json has always resolved peer dependencies for NPM dependencies to get the type information. If that doesn't sound right, please make an issue on the Typings repo so we can figure out how to improve this flow. However, if you reference it in your code you need to make sure types exist for it.

Edit: I'll submit another PR to make it act more like ambient dependencies, and you can give me feedback for 0.7 of Typings.