- add usage strings for short option such as '-a' for '--all'
This add all short options to usage text.
- add missing --header usage help for download command
- some cometic changes
Closes-bug: #1475511
Change-Id: Ibfecac8764669540fa025787548133a50fa50b10
Signed-off-by: Hiroshi Miura <miurahr@nttdata.co.jp>