INT-2120:RemoteFileTemplate - Phase III

JIRA: https://jira.spring.io/browse/INT-3205

* add SftpSessionFactoryResolver, DefaultSessionFactoryResolver, SftpSessionFactoryResolver
* add constructor in RemoteFileTemplate that take SessionFactoryResolver as parameter
* add test
I don't thik so: `tmpSessionFactory` is just for the current message. You must not mutate `RemoteFileTemplate`