scoped modules with specific versions fail to install

- **Version**: 2.3.2
- **Platform**: Darwin 15.6.0 Darwin Kernel Version 15.6.0: Thu Jun 23 18:25:34 PDT 2016; root:xnu-3248.60.10~1/RELEASE_X86_64 x86_64 i386 MacBookPro11,2 Darwin

ied fails when installing specific versions of scoped modules, likely due to https://github.com/npm/npm/issues/9164
which is an open issue of the npm registry api https://github.com/npm/public-api/issues/11

``` bash
➜ ied i @types/mocha@2.2.29

/Users/scott/.nvm/versions/node/v6.2.2/lib/node_modules/ied/node_modules/rxjs/Observer.js:5
error: function (err) { throw err; },
^
AssertionError: error status code https://registry.npmjs.org/@types%2Fmocha/2.2.29: undefined
at checkStatus (/Users/scott/.nvm/versions/node/v6.2.2/lib/node_modules/ied/lib/registry.js:97:20)
at SafeSubscriber._next (/Users/scott/.nvm/versions/node/v6.2.2/lib/node_modules/ied/lib/registry.js:134:12)
at SafeSubscriber.__tryOrSetError (/Users/scott/.nvm/versions/node/v6.2.2/lib/node_modules/ied/node_modules/rxjs/Subscriber.js:232:16)
at SafeSubscriber.next (/Users/scott/.nvm/versions/node/v6.2.2/lib/node_modules/ied/node_modules/rxjs/Subscriber.js:174:27)
at Subscriber._next (/Users/scott/.nvm/versions/node/v6.2.2/lib/node_modules/ied/node_modules/rxjs/Subscriber.js:125:26)
at Subscriber.next (/Users/scott/.nvm/versions/node/v6.2.2/lib/node_modules/ied/node_modules/rxjs/Subscriber.js:89:18)
at DoSubscriber._next (/Users/scott/.nvm/versions/node/v6.2.2/lib/node_modules/ied/node_modules/rxjs/operator/do.js:82:24)
at DoSubscriber.Subscriber.next (/Users/scott/.nvm/versions/node/v6.2.2/lib/node_modules/ied/node_modules/rxjs/Subscriber.js:89:18)
at /Users/scott/.nvm/versions/node/v6.2.2/lib/node_modules/ied/lib/util.js:91:14
at done (/Users/scott/.nvm/versions/node/v6.2.2/lib/node_modules/ied/node_modules/needle/lib/needle.js:377:14)
```

Scoped modules without versions work fine:

``` bash
➜ ied i @types/mocha
```