Issue #682: convert logs package to RFC5424 logging levels.

code style simplify

code style simplify

beego/context: Fix ignored Header in case SetStatus has been called before

Make redis cache timeout not trivial.

- Instead of using HASH for all the caches, use HASH + normal KEYs.
- HASH being used as a collection of all KEYs, this is useful when
  application wants to clear all keys.

修正Detect Engine错误

Generate default value while run ORM cmd tool

Makes RenderForm use textarea-element when form type is `textarea`

beego: fix #657

When RenderForm encounters a field with the structTag `form` value
type `textarea` it renders an actual <textarea> html tag.

Extracted a func `parseFormTag` that takes a reflect.StructField
and returns the different positional parts of the `form` structTag
with default values as documented in
http://beego.me/docs/mvc/view/view.md#renderform

This makes RenderForm shorter and makes it possible to test the
parsing separately.