blastCache = watcher => {
  const files = getWatchedFiles(watcher);
  files.forEach(file => {
    delete require.cache[file];
  });
  debug('deleted %d file(s) from the require cache', files.length);
}
Blast all of the watched files out of `require.cache`
@param {FSWatcher} watcher - chokidar FSWatcher
@ignore
@private