Add empty SpecInfra::Command::Base class
Replace SPEC_TYPE to SpecInfra
Add requirements for command classes
Cmmands -> Command
Now SpecInfra has Commands::Base class, so don't need to define a dummy class for testing
Move Serverspec::Commands::AIX to SpecInfra::Command::AIX
Copy all methods from Serverspec::Commands::Base
Move Command::Linux and Command::Debian from serverspec
Remove shellwords because it is required in base class
Move Command::Darwin from serverspec
Move Command::FreeBSD from serverspec
Move Command::Gentoo from serverspec
Move Command::Plamo from serverspec
Move Command::RedHat from serverspec
Move Command::Solaris* and Command::SmartOS from serverspec
Move Command::Windows from serverspec
Move Command::RedHat from configspec
Copy Commnand::Darwin from Syllabus
Merge pull request #5 from serverspec/integrate-commands

[WIP] Integrate Serverspec::Commands::*, Configspec::Commands::* and Syllabus::Command::* to specinfra