binding: support unix time (#1980)
* binding: support unix time
ref:#1979
* binding: support unix time
add test file
modify readme
```golang
package main
import (
"fmt"
"github.com/gin-gonic/gin"
"time"
)
type shareTime struct {
CreateTime time.Time `form:"createTime" time_format:"unixNano"`
UnixTime time.Time `form:"unixTime" time_format:"unix"`
}
func main() {
r := gin.Default()
unix := r.Group("/unix")
testCT := time.Date(2019, 7, 6, 16, 0, 33, 123, time.Local)
fmt.Printf("%d\n", testCT.UnixNano())
testUT := time.Date(2019, 7, 6, 16, 0, 33, 0, time.Local)
fmt.Printf("%d\n", testUT.Unix())
unix.GET("/nano", func(c *gin.Context) {
s := shareTime{}
c.ShouldBindQuery(&s)
if !testCT.Equal(s.CreateTime) {
c.String(500, "want %d got %d", testCT.UnixNano(), s.CreateTime)
return
}
c.JSON(200, s)
})
unix.GET("/sec", func(c *gin.Context) {
s := shareTime{}
c.ShouldBindQuery(&s)
if !testUT.Equal(s.UnixTime) {
c.String(500, "want %d got %d", testCT.Unix(), s.UnixTime)
return
}
c.JSON(200, s)
})
r.Run()
}
```
* Contraction variable scope
502c898d75