Swarm: redo file transfer logic [Wait for android implem]

• sendFile() only adds a message to the conversation, but don't send any request

• other peers download files or not

• logic is the same as askForTransfer

• URI should supports parameters like from/to to download a block

• If a socket is cut, it should retry to download

• Add ratio infos (peers transfer in progress)

TODO

+ rebase unit tests

+ Download file return TID file

+ relink cancelTransfer

+ shutdown channel avoid write both sides.

+ start offset support

+ remove istringstream

+ cache waiting transfers

+ add re-ask mechanism

+ Prepare patch to delete all deprecated code

+ Relink infos()

+ Check that all test builds

+ Move transferManager in conversation and logic from jamiaccount

+ rebase re-ask

+ sendProfile()

+ patch to remove all old logic

+ fileInfo (conv, interactionId, info)

+ cleanup code

+ add tests (info out/in ; retry ; info ; bytesProgress)

+ Update API