Initial log with log-level passed by MySQLOptions under options.

[Jacob953]

What type of PR is this?

bug

What this PR does / why we need it:

1. Pass LogLevel from options.MySQLOptions to db.MySQLOptions with copier.
2. Initial Logger if LogLevel between 1 and 4, which maps to Mode of Gorm(from Silence to Info). Otherwise, make it the default Logger of Gorm instead of Onex.

Which issue(s) this PR fixes:

Fixes #20

Special notes for your reviewer:

Thx for reviewing :)

[Jacob953]

@colin404 plz take a look. :)