Fix usage message

[sidiandi]

C:\work\rft\out\Debug\rft\bin>rft -h
Usage: program [option]... <command>

C:\work\rft\out\Debug\rft\bin>rft c --help
Usage: create-developer-branch [option]... [trunkServerItem: String]

Options in sub commands are not complete

One letter options are missing in usage instructions

program command --help for help

Display usage when called without args in multi-command mode

[sidiandi]

Still to do:

• Options in sub commands are not complete
• Display usage when called without args in multi-command mode

[sidiandi]

Still to do:

• Options in sub commands are not complete