function uploadFiles(dispatch, firebase, { files, ...other }) {
  return Promise.all(
    map(files, (file) => uploadFile(dispatch, firebase, { file, ...other }))
  )
}
Upload multiple files to Firebase Storage with option to store
file's metadata within Firebase Database
@param {Function} dispatch - Action dispatch function
@param {object} firebase - Internal firebase object
@param {object} opts - Options object
@param {string} opts.path - Storage path to write files to
@param {Array} opts.files - List of files to be uploaded
@param {string} opts.dbPath - Datbase path to write file meta data to
@returns {Promise} Resolves with array of meta objects
@private