Support several columns for unique indices.

You can now declare unique indices like so:

var User = sequelize.define('User', {
	username: {
		type: DataTypes.STRING,
		unique: {
			name: 'username_and_email',
			msg: 'Your username and email must be unique!'
		}
	},
	email: {
		type: DataTypes.STRING,
		unique: 'username_and_email'
	},
	aCol: {
		type: DataTypes.STRING,
		unique: true
	}
})

Will create two unique indices one for username/email combo and the
other for aCol. If a unique constraint occurs for aCol, the old behavior
still occurs (emits a dialect returned error), but for username/email
index the returned error would be, "Your username and email must be
unique!"
Merge branch 'master' into newindex

Conflicts:
	lib/dialects/sqlite/query-generator.js
Fixed tests.
Add testcase to test connection hang ups when a query is issued 100 ms after the last one (right when the client connection is closing)
Also added a possible fix
Fixed hashToWhereConditions and arrayValue in QueryGenerator to correctly handle in: and not: in where: conditions (fixes #1079)
Merge branch 'master' into hotfix/query_hangup
Fix CustomEventEmitter

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 typo
Merge pull request #1245 from saschagehlich/bugfix/customeventemitter-fix

Fix CustomEventEmitter
. fix unixSocket connection for mariadb
Merge pull request #1248 from mithrandirii/master

. fix unixSocket connection for mariadb
Merge pull request #1244 from iuriaranda/hotfix/query_hangup

New queries hang when a client connection is closed after the 100 ms period of inactivity
Update changelog.md
pool settings are not transported down to replica connections
Update connector-manager.js
Merge pull request #1251 from evantahler/master

pool settings are not transported down to replica connections
Update changelog.md
Update changelog.md
added transaction support
added a test for long running transactions