Fix multiple assocations with same table for belongsTo and hasOne.

If specifying an "as" in the options, use that as the associationAccessor
instead of the table name to prevent being overridden.

lib/associations/belongs-to.js

@@ -13,7 +13,7 @@ module.exports = (function() {
 
     this.associationAccessor = this.isSelfAssociation
       ? Utils.combineTableNames(this.target.tableName, this.options.as || this.target.tableName)
-      : this.target.tableName
+      : this.options.as || this.target.tableName
   }
 
   // the id is in the source table

lib/associations/has-one.js

@@ -13,7 +13,7 @@ module.exports = (function() {
 
     this.associationAccessor = this.isSelfAssociation
       ? Utils.combineTableNames(this.target.tableName, this.options.as || this.target.tableName)
-      : this.target.tableName
+      : this.options.as || this.target.tableName
 
     this.accessors = {
       get: Utils._.camelize('get_' + (this.options.as || Utils.singularize(this.target.tableName))),