[CMake] CPack option naming and deb generator

[Bill Hoffman]

I have been busy and have not had time to look at this thread.  I have 
also not had
a proper chance to look at the the generators that were added to CPack.
My gut feeling is that all variables should stay prefixed with CPACK_.  
CPACK_DEBIAN_XXXX.    Keeps us from polluting the global namespace
with arbitrary names and it lets you know that the variable is for use 
in CPack.

-Bill