update latest xorm version to vendor (#2353)

vendor/github.com/go-xorm/xorm/doc.go

@@ -8,7 +8,7 @@ Package xorm is a simple and powerful ORM for Go.
 
 Installation
 
-Make sure you have installed Go 1.1+ and then:
+Make sure you have installed Go 1.6+ and then:
 
     go get github.com/go-xorm/xorm
 
@@ -51,11 +51,15 @@ There are 8 major ORM methods and many helpful methods to use to operate databas
     // INSERT INTO struct1 () values ()
     // INSERT INTO struct2 () values (),(),()
 
-2. Query one record from database
+2. Query one record or one variable from database
 
     has, err := engine.Get(&user)
     // SELECT * FROM user LIMIT 1
 
+    var id int64
+    has, err := engine.Table("user").Where("name = ?", name).Get(&id)
+    // SELECT id FROM user WHERE name = ? LIMIT 1
+
 3. Query multiple records from database
 
     var sliceOfStructs []Struct
@@ -99,6 +103,9 @@ another is Rows
     counts, err := engine.Count(&user)
     // SELECT count(*) AS total FROM user
 
+    counts, err := engine.SQL("select count(*) FROM user").Count()
+    // select count(*) FROM user
+
 8. Sum records
 
     sumFloat64, err := engine.Sum(&user, "id")