Login with github, google or guest mode fails.

[JUHYUNCHOI]

Sometimes, login with github, google or guest mode failes.

[kyungmi]

@JUHYUNCHOI In case of 'Google login', that was just caused by a recent network problem. But the reason of 'Github login' issue was more complicated and I resolved the issue with PR #116.
Unfortunately, I haven't gotten realize what is the real problem with the 'guest login' yet.

[kyungmi]

@JUHYUNCHOI
You can try to login with Github or Google again.
For the remain 'guest login' issue, I wrote another issue #117