fatal which now use os._exit, lack of a return code.

The watch command uses a buffer instead of the standard output. Using this the watch
command can execute commands and wait the end of the execution to clear and print the buffer.
The watch command also catch cliException and KeyboardInterrupt in order to proceed to clean exit.

The time command now catch the ccli exception and KeyboardInterrupt and
print the execution time before a clean exit.

Clear function used to check if sys.stdout was a tty and didn't allow you to use clear in an other
fd. This check has been deleted in this patch and you can now use clear in a buffer

clearing terminal is now a function of class  Printer.
Command clear, now use it.

The fd default argument in the out and err fonction causes bad issues because it was initialized
when the class was instanciated. Consequently this patch set the default argument to None and permit you
to change the stdout and stderr file descriptor without causing troubles

Commands loading is now done by crawling commands directory under cccli module.
All command which starts by Commmand_ and which is a son of Command class are candidate.

When server disconnect cli is hardly killed and history is not saved.
Now we just warn about disconnection

Introduce new class RemoteCommand, which help checking needed remote functions are available
before adding a command to list of commands

Signed-off-by: Seblu <sebastien.luttringer@smartjog.com>

Signed-off-by: Seblu <sebastien.luttringer@smartjog.com>

Signed-off-by: Seblu <sebastien.luttringer@smartjog.com>