rsshfs

Fixed umount which was stuck when the ssh connection was not available

Fixed doc regarding latest changes

Implemented a way to differenciate -o param for SSHFS or for SSH (SSH opts begin with capital letter, and except only one, SSHFS opts begin with small letter)

Added the possibility to pass SSH options. Rewrote the args parsing. Added a feature to put it in background. Added a help.

Add a new unmounting method in README