Update captcha.go

Captcha must be deleted if the user entered a "challenge" with a different length than the captcha.
Merge pull request #729 from francoishill/patch-9

Update captcha.go
make the getconfig public

// Getconfig throw the Runmode
// [dev]
// name = astaixe
// IsEnable = false
// [prod]
// name = slene
// IsEnable = true
//
// usage:
// GetConfig("string", "name")
// GetConfig("bool", "IsEnable")
delete forms
improve the 'geturl'

If we have a url mapping like this:
`beego.Router(“/test”, &controllers.WeightController{},
"get:GetDetails”)`
when u use `UrlFor(“WeightController.GetDetails”, “foo”, 1, “bar”, 2 `,
it should return `/test?foo=1&bar=2` rather than `/test`.
Merge pull request #733 from liulixiang1988/develop

improve the 'geturl'
fix the regexps bugs
beego: fix the tree addTree for regexp
beego: fix the addTree