Update error format for postgresql

`node-libpq` now exposes more detailed error information.

lib/dialects/postgres/query.js

@@ -256,10 +256,14 @@ module.exports = (function() {
       , table
       , index;
 
-    switch (err.code) {
+    var code = err.code || err.sqlState
+      , errMessage = err.message || err.messagePrimary
+      , errDetail = err.detail || err.messageDetail;
+
+    switch (code) {
       case '23503':
-        index = err.message.match(/violates foreign key constraint \"(.+?)\"/)[1];
-        table = err.message.match(/on table \"(.+?)\"/)[1];
+        index = errMessage.match(/violates foreign key constraint \"(.+?)\"/)[1];
+        table = errMessage.match(/on table \"(.+?)\"/)[1];
 
         return new sequelizeErrors.ForeignKeyConstraintError({
           fields: null,
@@ -270,7 +274,7 @@ module.exports = (function() {
       case '23505':
         // there are multiple different formats of error messages for this error code
         // this regex should check at least two
-        match = err.detail.match(/Key \((.*?)\)=\((.*?)\)/);
+        match = errDetail.match(/Key \((.*?)\)=\((.*?)\)/);
 
         if (match) {
           var fields = Utils._.zipObject(match[1].split(', '), match[2].split(', '))
@@ -299,7 +303,7 @@ module.exports = (function() {
           });
         } else {
           return new sequelizeErrors.UniqueConstraintError({
-            message: err.message,
+            message: errMessage,
             parent: err
           });
         }