update postgresql error message parsing on foreign key

Error code: 23503

On "recent" postgresql (> 8?), error message is:
insert or update on table "$table" violates foreign key constraint
"$index"

I updated the error match to get the right table and index in both
cases.

Before this patch, sequelize failed badly with: `TypeError: Cannot read
property '1' of null`
add check for another error message
Merge pull request #2393 from vvo/fix-pgsql-constraint-message

update postgresql error message parsing on foreign key
Add: CounterCache feature to hasMany models
Merge pull request #2375 from Kuzmin/master

Add: CounterCache feature to hasMany models
Fix: Model.count() and findAndCountAll() returned NaN with Postgres and quoteIdentifiers==false.
make regex parsing more lenient
add break statement
Added test case to demonstrate issue #2316
sequelize error picks up message from db err
Merge pull request #2395 from vpontis/error-parsing

add different error format for 23505 error on postgres
sequelize/sequelize#2418 Don't overwrite autocommit setting for an outer transaction when using findOrCreate
Merge pull request #2419 from sheltond/master

sequelize/sequelize#2418 Don't overwrite autocommit setting for an outer transaction when using findOrCreate - closes #2418
possible fix for manyToMany relationships using indexes
possible fix for #2416 by dropping indexes from the creation of many-to-many relation tables
unit test against #2416
Merge branch 'master' of https://github.com/sequelize/sequelize
Merge pull request #2422 from nullivex/master

Fixes #2416 - Creation of Many-to-Many associations using indexes
Update changelog.md
Merge branch 'master' of https://github.com/haches/sequelize into haches-master