Adoptions to use refactored version of CLAP

[Ducasse]

This is super cool to get your help to improve CLAP thanks a lot.

[Bajger]

@demarey Hi Christophe! I think I've finally made all necessary changes to use new CLAP! Please take a review and let me know. Some insights:

• there is just one failing test at the moment -> PhLImageCreateFromPullRequestCommandTest>>testExecuteFromPR due to fact it relies on Network. Any ideas how to plug PhLImageFinderStub (that would give hardcoded replies) instead of PhLImageFinder
• PhLImageCreateFromSHACliCommandTest>>testCreateImageFromShaShouldSucceed also relies on Network
• help command prints default help message for clap command but not for concrete subcommands. Any ideas what might be wrong?

PS: If you don't mind, I'd like to merge PR then.

[Bajger]

@demarey: Incorporated review comments. Now I need to resolve following on CLAP:

• resolve printHelp problem
• add convenient method to separate first 3 lines on ClapContext>>executeToExit:, so I can bypass ImageFinder class on command instance in unit tests that rely on network.