[Yum] another 'reverse logic'

[bor@xxxxxxxx (Vladimir Bormotov)]

                Hi!
  
  clientStuff.checkGPGInstallation() return 0 if success...
  
  And this function used only in pkgaction.checkRpmSig(), I think
  pkgaction.py better place for it's declaration.
  
-- 
		Bor.