[Connect/Streams] Refactoring the file structure to be inline with subcomponent guidelines.
[Connect/Mail] Added a Mail Message interface (tbr).
[Connect/Streams] Stream interface: size() -> getSize()
[Connect/Streams] Refactoring the Stream class (WIP).
[Connect/Mail] Added a Mail Handler interface.
[Connect/Mail] Added a Swift Mailer handler and a generic Message class based on Swift Mailer as well.