Allow calling components/pipelines from code

[yamalight]

Allow executing components and pipelines as part of code.
This can significantly improve flexibility of the system.

Imported code should be a promise/observable due to the nature of the platform (we'll need to pre-compile it on server before it can be used).

Example pseudo-code:

import componentPromise from 'user/c/component'; // or 'user/p/pipeline'
export default (data) => Rx.Observable.create(obs => {
    componentPromise.then(component => component(data).subscribe(obs));
});