Update INSTALL.md

Updated bitcoind apt-get install line, cause independent libboost packages implies 1.46 version dependecies: This is solved with just libboost1.48-* install


(libboost-filesystem-dev : Depends: libboost-filesystem1.46-dev but it is not going to be installed
 libboost-program-options-dev : Depends: libboost-program-options1.46-dev but it is not going to be installed
 libboost-system-dev : Depends: libboost-system1.46-dev but it is not going to be installed
 libboost-thread-dev : Depends: libboost-thread1.46-dev but it is not going to be installed
E: Unable to correct problems, you have held broken packages.)