Updated configure.ac and build-unix.md to instruct about Ubuntu 13.10 and libboost1.54-all-dev error.

Updated configure.ac and build-unix.md to instruct about Ubuntu 13.10 and libboost1.54-all-dev error. If using Ubuntu 13.10 with libboost1.54-all-dev you must remove libboost1.54-all-dev and install libboost1.53-all-dev instead.