'sbc-startup' is now 'sbc shell'. Fix #19
Remove 'sbc install' and add 'sbc setup'. Fix #21
Fix SBC environment variables
Update README
Add remote sub-command to retrieve setup. Fix #18

This sub-command (configure) should be run only by sbc itself (when user calls
'sbc setup' and do all the things needed to copy the private key from local to
remote server).
Move ControlPath to /tmp
Move local env file to /tmp
Create local $HOME/.ssh if doesn't exist
Fix problem with fish shell. Thanks @kurtkraut
Merge branch 'feature/fix-startup-and-install' into develop