login(credentials) {
  let params = {
    username: credentials.email.toLowerCase(),
    password: SHA3(credentials.password).toString()
  };

  return new Promise((resolve, reject) => {
    this.http.post(API + '/auth/login', params)
      .map(res => res.json())
      .subscribe(data => {
          localStorage.setItem('user', JSON.stringify(data.user));
          resolve(true);
        });
      },
      error => {
        reject(Error(error._body));
      });
  });
}

Cordova CLI: 6.3.1
Ionic CLI Version: 2.2.1
Ionic App Lib Version: 2.2.0
OS: Linux 4.4
Node Version: v7.8.0
express: 4.15.2
couchdb-promises: 3.0.0