Help command

I did some improvements and fixes in this PR to ensure that all commands and options described in `help.txt` are working properly.
Avoid boolean method arguments - it's impossible to tell what this switch does without going to the method definition.
http://ariya.ofilabs.com/2011/08/hall-of-api-shame-boolean-trap.html

Maybe a second overload will work best here `validatePlatform(platform)` and `validatePlatformInstalled(platform)`