public / sequelize

Make sure that objects passed to CustomEventEmitter's `error` event
are boiled down to real Error instances so that node's EventEmitter
does not give us this nasty "Uncaught, unspecified error" thing.

Fix CustomEventEmitter error handling

Override .emit() to first check whether the error argument is an array. In case
it is an array, reduce it to the very first error and pass it to the original
EventEmitter.emit()

Sequelize.ENUM: Values as arguments / array

Added tests for both field: Sequelize.ENUM and field: { type: Sequelize.ENUM }

Fix for #1234 - Postgres query should set on .dataValues instead of object

Validation skipping logic was inverted. Fixed #1169

better check if 'IS NOT' or '!=' should be used

Conflicts:
	bin/sequelize

Tests/Fixes for undoing migrations.

Fix/Tests for #1218

Now passing instances to hooks