Finished the support of partial compilation and packaging in cmake.

 The full set of packages can be compiled straight with the following sequence:
   rm -rf ../build/; mkdir ../build; (cd ../build/; cmake ../castor-git/ ); make -C ../build/ castor_rpm
 The client packages can also be build directly by adding an option at cmake time:
   rm -rf ../build/; mkdir ../build; (cd ../build/; cmake -DCOMPILE_SERVER:STRING=0 ../castor-git/ ); make -C ../build/ castor_rpm
 Finally, one can use the srpm as a first step, and use the TeamCity compatible rpmbuild switch "clientonly":
   rm -rf ../build/; mkdir ../build; (cd ../build/; cmake ../castor-git/ ); make -C ../build/ castor_srpm
   buildtree=`mktemp -d`; mkdir -p ${buildtree}/{RPMS/{i386,i586,i686,x86_64},SPECS,BUILD,SOURCES,SRPMS};
   rpmbuild --define "_topdir ${buildtree}" --define "clientonly 1" --rebuild ../build/RPM/SRPMS/castor-2.1.14-4.el6.src.rpm