* remove github.com/unknwon/com from models
* dont use "com.ToStr()"
* replace "com.ToStr" with "fmt.Sprint" where its easy to do
* more refactor
* fix test
* just "proxy" Copy func for now
* as per @lunny
* move transfer repository and rename repository on a service package and start action notification
* remove unused codes
* fix lint
* fix bugs
* fix test
* fix test
* fix test
* fix lint
* update go mod and sum