Option to render CSS into component

[p3k]

This PR adds the option less.component to the RequireJS config and – if set to true – renders the LESS code as CSS into the component where it was required from.

We are currently using this to enable LESS in RactiveJS components.

Example:

import Ractive from 'ractive';
import css from 'less!./App';
import template from 'text!./App.html';

const App = Ractive.extend({
  template,
  css
});

export { App };

Furthermore, the cless.js and cless-builder.js wrappers allow per-file CSS output to a component; just use these as replacement plugin like import css from 'cless!/.App'.

Would be glad if you considered this, please let me know what you think.