Added MultipeerConnectivity support v1

Another try.
All the MultipeerConnectivity code is now in MyMultipeerImplementation file which is not part of Ensembles (the developers will have their own implementation).

CDEMultipeerCloudFileSystem now has 3 public methods:

`- (BOOL)synchronizeFilesViaMultipeerSession:(MCSession *)session withSpecificPeers:(NSArray *)specificPeers;` -> it just sends other peers what it has locally. In my implentation is send data at each saves, but it be called on a UI action or a timer.

`- (void)handleMessageData:(NSData *)data fromPeer:(MCPeerID *)peerID inSession:(MCSession *)session;` -> MyMultipeerImplementation calls this method when it receives data (a message, not the actual files)

`- (void)importArchiveAtURL:(NSURL *)archiveURL archiveName:(NSString *)archiveName;` -> -> MyMultipeerImplementation calls this method when it receives a file (the archive with the actual files)