updateOverview (overview) {
    store.commit('SET_OVERVIEWS_ERROR', '');

    return new Promise((resolve, reject) => {
      fetch(`api/overview/${overview._id}`, {
        method: 'PUT',
        headers: setReqHeaders({ 'Content-Type': 'application/json' }),
        body: JSON.stringify(overview)
      }).then((response) => {
        return response.json();
      }).then((response) => {
        if (response.success) {
          store.commit('UPDATE_OVERVIEW', overview);
          return resolve(response);
        } else {
          store.commit('SET_OVERVIEWS_ERROR', response.text);
          return reject(response.text);
        }
      });
    });
  }
Updates an overview.
@param {Object} overview - The new overview data
@returns {Promise} - The promise that either resolves the request or rejects in error