Add namespaces

Input
```
export namespace iAppConfig {
export interface ServiceConfig {
key: string;
token: string;
}
}
```

Output is for empty file:
```
/**
* This module was automatically generated by `ts-interface-builder`
*/
import * as t from "ts-interface-checker";
// tslint:disable:object-literal-key-quotes
const exportedTypeSuite: t.ITypeSuite = {
};
export default exportedTypeSuite;
```

Quick fix - just to ignore namespaces