Prevent `log` options from being dumped to log

This commit (https://github.com/sequelize/sequelize/commit/6147c8e814494dcaf33adf614d07276f4ecc605b) made logging more customizable, but introduced a bug: All options passed to `sequelize.log` where also dumped to log file. This revision removes the options from the set of logged arguments.
Merge pull request #2732 from Domiii/patch-1

Prevent `log` options from being dumped to log