Edit: configure.am and doc/build-unix.md for Ubuntu 13.10 with libboost1.54-all-dev incompatibility

Edit: configure.am and doc/build-unix.md for Ubuntu 13.10 users to deal with very messy issue with Ubuntu Saucy 13.10 and libboost1.54-all-dev because Ubuntu is now using multi architecture libs for 64 bit systems but libboost1.54-all-dev was looked over this time, so libboost1.53-all-dev works on Saucy 13.10 and libboost1.54-all-dev will work in Trusty but libboost1.54-all-dev does not work to build Bitcoin with Ubuntu Saucy 13.10 and configure will return error: 'Could not link against libboost::chrono !' because the boost libs are placed in different locations for 1.53 and 1.54.