release(3.1.0)

changelog.md

-# next
+# 3.1.0
 
 - [BUG] Fix an issue with the build in isIP validator returning false negatives [#3756](https://github.com/sequelize/sequelize/pull/3756)
 - [ADDED] It is now possible to defer constraints in PostgreSQL by added a property `deferrable` to the `references` object of a field.

package.json

 {
   "name": "sequelize",
   "description": "Multi dialect ORM for Node.JS/io.js",
-  "version": "3.0.1",
+  "version": "3.1.0",
   "author": "Sascha Depold <sascha@depold.com>",
   "contributors": [
     {