Problems in dependency resolution

Hello @andreypopp. Thanks for the great library! I have been using it a little and I have found several big problems. The main problem right now is that is doesn't collect all the files that TypeScript needs. Consider this code from your library:

https://github.com/andreypopp/typescript-loader/blob/master/lib/TypeScriptWebpackHost.js#L177-L193

``` typescript
TypeScriptWebpackHost.prototype._addDependencies = function(resolver, filename) {
var dependencies = this._findImportDeclarations(filename).map(function(dep) {
return this._resolve(resolver, filename, dep).then(function(filename) {
var alreadyExists = this._files[filename];
var added = this._readFileAndAdd(filename);
// This is d.ts which doesn't go through typescript-loader separately so
// we should take care of it by analyzing its dependencies here.
if (/\.d.ts$/.exec(filename) && !alreadyExists) {
added = added.then(function() {
return this._addDependencies(resolver, filename);
}.bind(this));
}
return added;
}.bind(this));
}.bind(this));
return Promise.all(dependencies);
}
```

In this function you traverse only one level of the regular (non `.d.ts`) dependencies. But to compile the file TS needs the _whole dependency tree_ to be loaded into the service.

We don't see any errors because [here](https://github.com/andreypopp/typescript-loader/blob/master/lib/TypeScriptWebpackHost.js#L212-L215) you collect only current file diagnostics, but the actual errors are **in the file deps**.

Several days ago I have forked your library to [awesome-typescript-loader](https://github.com/s-panferov/awesome-typescript-loader) and completely rewritten all the things there.

I wrote this issue because:
1. I want to warn you and your users about the problem.
2. If you want I can explain all the changes I made there so you could port them to your library if you want.

I added the info about your authorship into the README, but your project doesn't contain the LICENSE file so just say if you want me to add some additional copyright notice.