scripts/install_xtuple: fix bad comment line
scripts/install_xtuple: ignore error backing up previous log file
scripts/install_xtuple: ignore error dropping previous DB
scripts/install_xtuple: check for sudo and install other key tools using apt
scripts/install_xtuple: use add-apt-repository instead of manipulating files manually
scripts/install_xtuple: remove hardcoded reference to Ubuntu precise, detect distribution dynamically
scripts/install_xtuple: add support for wheezy using wheezy-backports