Remove temporary typings workaround

[dsebastien]

There is an issue with the way that gulp-typescript (the plugin used within the scripts-typescript gulp task) handles the 'rootDir' property, which is inconsistent with tsc.

To solve this, for now, we've added a /// reference to the main.d.ts typings file to ensure that typings are taken into account when transpiling via gulp-typescript.

The final solution might come via the following issues and might require a new release of this project

• Option to emit referenced files. ivogabe/gulp-typescript#190
• Configure typings directory? typings/typings#69