#### Summary

The usage of btoa for basic auth prevents usage of non latin characters
Not really a big deal as you do not have to use the basic auth and can encode it yourself but thought I'd bring it up at least as passwords are becoming more unique. 

https://github.com/axios/axios/blob/0499a970d7064d15c9361430b40729d9b8e6f6bb/lib/adapters/xhr.js#L42

To reproduce try using a password with basic auth that has a ҂ symbol in it or by opening up a console and trying to use the btoa function on a string with a ҂ symbol.

test/specs/__helpers.js
jasmine.Ajax.uninstall();
  });
  it('should accept HTTP Basic auth with username/password', function (done) {
    axios('/foo', {
      auth: {
        username: 'Aladdin',
        password: 'open sesame'
      }
    });
    setTimeout(function () {
      var request = jasmine.Ajax.requests.mostRecent();
      expect(request.requestHeaders['Authorization']).toEqual('Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==');
      done();
    }, 100);
  });
  it('should fail to encode HTTP Basic auth credentials with non-Latin1 characters', function (done) {
    axios('/foo', {
      auth: {
        username: 'Aladßç£☃din',
        password: 'open sesame'
      }
    }).then(function(response) {
      done(new Error('Should not succeed to make a HTTP Basic auth request with non-latin1 chars in credentials.'));
    }).catch(function(error) {
      validateInvalidCharacterError(error);
      done();
    });
  });
};