public / sequelize

Update usage doc

Add unique keys check to postgres

Prevent `log` options from being dumped to log

Quote the name of unique indexes, and allow newlines in uniqe key names

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.

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

…changes attributes alone), closes #2341