Add missing -h/--help flag to several rails command

I just realize there're severals rails command that doesn't print help or usage message on calling -h/--help. This patch will make those commands print out usage when calling with -h/--help

Those commands I found are:

* rails generate -h / rails generate --help
* rails destroy -h / rails destroy --help
* rails benchmarker -h / rails benchmarker --help
* rails profiler -h / rails profiler --help

I also update rails console -h to print out description of --irb as deprecated, since if you called rails console -h, --irb description would be left blank.

Sikachus-Notebook:test_edge sikachu$ rails console -h
Usage: console [environment] [options]
    -s, --sandbox                    Rollback database modifications on exit.
        --debugger                   Enable ruby-debugging for the console.
        --irb