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.
make UniqueConstraintError inherit ValidationError

Unique constraint errors are in fact a different type of validation
error, run on the database level. While important to make a destinction
internally when we have encountered a UniqueConstraintError vs a normal
ValidationError, on the user side they should be represented the same.
This patch allows these exceptions to provide data in the same fashion
making it easier to uniformly process the errors
Failing test case for issue #2749
fix(includes): better support for merging paranoid where and subquery creating include where
Merge branch 'markwainwright-test-case-for-issue-2749'
Update changelog.md
Merge pull request #2760 from mbroadst/unique-constraint-to-validation

make UniqueConstraintError inherit ValidationError
Update changelog.md
feat(associations): belongsTo association setter now supports {save: false}, closes #2582
fix: don't assume options is set in belongsTo setter
fix: initial foreign key value can be undefined or null currently depending on RETURNING
avoid cryptic errors by checking for transaction

Without checking for this.transaction, a simple "access denied" error turns into the cryptic "cannot call commit on undefined" error.
Merge pull request #2782 from cdibbs/master

avoid cryptic errors by checking for transaction
Quote the name of unique indexes, and allow newlines in uniqe key names
Merge pull request #2789 from janmeier/master

Quote the name of unique indexes, and allow newlines in uniqe key names
Merge pull request #2732 from Domiii/patch-1

Prevent `log` options from being dumped to log
Add unique keys check to postgres
[feat] expose .changed() in .afterUpdate hooks, closes #2674
Merge pull request #2806 from seegno/bugfix/add-unique-keys-check

Add unique keys check to postgres
changelog entry for #2806