Fix: Tear down

This PR addressed some bugs.

 - [Patch] Fixed that FirstClassTestAttribute doesn't tear down, which is to
  execute a Dispose method.
  
- [Patch] Fixed that TestBaseAttribute does not tear down. This patch
  introduced breaking-changes but was included to this patch-version release
  because this bug should be addressed as soon.
  
    BREAKING-CHANGES
      - NEW: ITestCase2.Target
  
- [Patch] Fixed that the TestCommandContext.GetArguments method isn't
  implemeted accidentally.
  
- [Patch] Fixed that CompositeTestCommandFactory creates any commands when
  returning just an Enumerable object.