Update SessionExist to close the db connection

close the mysql connection
Merge pull request #463 from NormanZhang/develop

Update SessionExist to close the db connection
add coding
add Strings interface can return []string sep by ;

Example:
peers = one;Two;Three
add captcha util
add some comments for captcha
Update README.md
Merge pull request #468 from cloudaice/patch-1

Update README.md
add readme for captcha, and enhanced performance
add comments for middleware packages, fix typo error
add comments for orm packages, part 1
add comments for orm packages, part 2
add comments for orm package, done
Merge pull request #1 from fuxiaohei/develop

merge develop
Merge pull request #470 from fuxiaohei/develop

add comments for orm and middleware packages.
diffrent level logs display diffrent color
fix bug, redis session doesnt work
Merge pull request #473 from cloudaice/logs-feature

diffrent level logs display diffrent color
Add a ReadOrCreate method:

m := &User{Name: "Kyle"}
// Returns a boolean indicating whether the object was created,
// the primary key of the object, or an error.
created, id, err := orm.ReadOrCreate(m, "Name")
bug fix, session stored in redis cannot be deleted