Feature/rsync task

 Executes rsync in a flexible manner.
 
 ``` php
 $this->taskRsync()
   ->fromPath('src/')
   ->toHost('localhost')
   ->toUser('dev')
   ->toPath('/var/www/html/app/')
   ->recursive()
   ->excludeVcs()
   ->checksum()
   ->wholeFile()
   ->verbose()
   ->progress()
   ->humanReadable()
   ->stats()
   ->run();
 ```
 
 You could also clone the task and do a dry-run first:
 
 ``` php
 $rsync = $this->taskRsync()
   ->fromPath('src/')
   ->toPath('example.com:/var/www/html/app/')
   ->archive()
   ->excludeVcs()
   ->progress()
   ->stats();
 
 $dryRun = clone $rsync;
 $dryRun->dryRun()->run();
 if ('y' === $this->ask('Do you want to run (y/n)')) {
   $rsync->run();
 }
 ```