Start doc with "Package dou is ...". Follow golint.
Rename type ApiStatus to APIStatus. Follow golint.
Rename type jsonapi.jsonApi to jsonapi.jsonAPI. Follow golint.
Rename local var gotJson to gotJSON. Follow golint.
Add doc to dou.Config. Follow golint.
Add doc to dou.NewSafeWriter. Follow golint.
Fix typo
Rename *Api* to *API*. Follow golint.
Don't capitalize error strings. Follow golint.
Add doc to User in example/full/mail.go. Follow golint.
Add doc for ApiStatus* in example/full/main.go. Follow golint.