Fix bug when using postgresql 8.x

BUG: error: unterminated quoted string at or near
\"'\\' ORDER BY \"uuid\"\" when using like filter.
eg. { where: {name: {like: "%abc%"}}}

Author: tmclouisluk

lib/postgresql.js

@@ -387,10 +387,10 @@ PostgreSQL.prototype.buildExpression = function(columnName, operator,
     operatorValue, propertyDefinition) {
   switch (operator) {
     case 'like':
-      return new ParameterizedSQL(columnName + " LIKE ? ESCAPE '\\'",
+      return new ParameterizedSQL(columnName + " LIKE ? ESCAPE '\\\\'",
           [operatorValue]);
     case 'nlike':
-      return new ParameterizedSQL(columnName + " NOT LIKE ? ESCAPE '\\'",
+      return new ParameterizedSQL(columnName + " NOT LIKE ? ESCAPE '\\\\'",
           [operatorValue]);
     case 'regexp':
       if (operatorValue.global)