fix(server): start if no write permmision for logdir

[kotakanbe]

What did you implement:

./go-cve-dictionary server
EROR[02-02|06:17:49] Failed to create a log file              err="open /var/log/vuls/cve-dictionary.log: permission denied"
INFO[02-02|06:17:50] Starting HTTP Server...
EROR[02-02|06:17:50] open /var/log/vuls/access.log: permission denied

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

./go-cve-dictionary server
EROR[02-02|07:13:47] Failed to create a log file              err="open /var/log/vuls/cve-dictionary.log: permission denied"
INFO[02-02|07:13:47] Starting HTTP Server...
EROR[02-02|07:13:47] Failed to create a log file: open /var/log/vuls/access.log: permission denied
INFO[02-02|07:13:47] Listening on 127.0.0.1:1323

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⇨ http server started on 127.0.0.1:1323

Checklist:

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• Write tests
• Write documentation
• Check that there aren't other open pull requests for the same issue/feature
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• Pass the test by make test
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Is this ready for review?: YES