Adds support for Sequelize.DECIMAL, which takes optional arguments for precision…

… and scale.  Fixes #232

lib/data-types.js

@@ -8,5 +8,12 @@ module.exports = {
   FLOAT: 'FLOAT',
   NOW: 'NOW',
   ENUM: 'ENUM',
+  get DECIMAL() {
+    var ret = function(precision, scale) {
+      return 'DECIMAL(' + precision + ',' + scale + ')';
+    };
+    ret.toString = ret.valueOf = function() { return 'DECIMAL'; };
+    return ret;
+  },
   ARRAY: function(type) { return type + '[]' }
 }

spec/data-types.spec.js

+if(typeof require === 'function') {
+  const buster    = require("buster")
+      , Sequelize = require("../index")
+      , Helpers   = require('./buster-helpers')
+      , dialect   = Helpers.getTestDialect()
+}
+
+buster.spec.expose()
+
+describe(Helpers.getTestDialectTeaser('Data types'), function() {
+  if (dialect == 'mysql') {
+    it('should return DECIMAL for the default decimal type', function() {
+      expect(Sequelize.DECIMAL).toEqual('DECIMAL');
+    });
+
+    it('should return DECIMAL(10,2) for the default decimal type with arguments', function() {
+      expect(Sequelize.DECIMAL(10, 2)).toEqual('DECIMAL(10,2)');
+    });
+  }
+});