Code review comment for lp:~milo/linaro-ci/bug1034288

Some minor fixes:
1) Add the function call where we need it (Oneiric/Precise node). Skip Natty node for now.
2) Rename install_lit to lit_install for consistency with live_build_install.
3) Call the function between live_build_install and git_config, to keep the packages installation block together.
4) VERSION should contains the debian version i.e. 2012.09.1-0ubuntu1~linaro1
5) use a single wget i.e. wget "${DOWNLOAD_URL}${DEB_FILE} ${DOWNLOAD_URL}${PYTHON_LIT}"

Thanks!