[CMake] CMake and RPM documentation update

[Eric Noulard]

Hi all,

I've just updated documentation regarding CMake
and forthcoming CPack RPM generator.

There is still work to be done but the generator
is functional for binary RPM.

http://www.cmake.org/Wiki/CMake:CPackPackageGenerators#RPM_.28Unix_Only.29

I have added some explanation on the differences
between UseRPMTools and CPack RPM generator

http://www.cmake.org/Wiki/CMakeUserUseRPMTools#CPack_Built-in_RPM_support_design_issues

It deserve a feature request.
I'll post one soon.
I did want to put the information there for public access since
until now it was only provided as private e-mail.

I lack time to go on this for the moment so I would
rather put it public if anyone is wanting to go on before I found more time.

-- 
Erk