-[INTERNALS] Update `inflection` dependency to v1.5.3
-[FEATURE] Replaced string error messages for connection errors with error objects. [#2576](https://github.com/sequelize/sequelize/pull/2576)
-[FEATURE] Support for updating fields on duplicate key in bulk update (mysql only) [#2692](https://github.com/sequelize/sequelize/pull/2692)
-[FEATURE] Basic support for Microsoft SQL Server
#### Backwards compatability changes
- Some of the string error messages for connection errors have been replaced with actual error instances. Checking for connection errors should now be more consistent.
