Split npm start into an init and watch script
Split npm start into an init and watch script

This is to better support riot-web's build process without losing the functionality supplied by `npm start`. The watch script no longer performs an initial build and thus `start:init` has been created for this purpose. 
matrix-org/matrix-js-sdk,matrix-org/matrix-js-sdk,matrix-org/matrix-js-sdk,krombel/matrix-js-sdk,krombel/matrix-js-sdk,matrix-org/matrix-js-sdk,krombel/matrix-js-sdk