Add ONLY_KLEO to build only libkleopatra and kleopatra, and KLEO_ONLY_UISERVER, which builds libkleo with only core and gpgme backend, and kleopatra w/o mainwindow. Brings down the ldd|wc -l count to 47. We also can do w/o libkabc now.

svn path=/branches/work/kdab-post-4.0/kdepim/; revision=712453