Run the $SHELL with TERM=vt100 to avoid problems with zsh

Without setting the ``$TERM`` and in case ``$SHELL`` happens to be zsh the ``exec-path`` becomes the following when the script is run at init time from ``init.el``:

    ("tput" " No value for $TERM and no -T specified
    tput" " No value for $TERM and no -T specified
    tput" " No value for $TERM and no -T specified
    tput" " No value for $TERM and no -T specified
    tput" " No value for $TERM and no -T specified
    tput" " No value for $TERM and no -T specified
    tput" " No value for $TERM and no -T specified
    tput" " No value for $TERM and no -T specified
    tput" " No value for $TERM and no -T specified
    tput" " No value for $TERM and no -T specified
    tput" " No value for $TERM and no -T specified
    tput" " No value for $TERM and no -T specified
    tput" " No value for $TERM and no -T specified
    tput" " No value for $TERM and no -T specified
    tput" " No value for $TERM and no -T specified
    tput" " No value for $TERM and no -T specified
    tput" " No value for $TERM and no -T specified
    tput" " No value for $TERM and no -T specified
    tput" " No value for $TERM and no -T specified
    tput" " No value for $TERM and no -T specified
    /usr/local/bin" "/usr/local/sbin" "/bin" "/usr/sbin" "/sbin" "/usr/bin" "/usr/X11/bin" "/usr/local/mysql/bin" "/Users/rauhahe/bin" "/usr/local/share/npm/bin
    ")
    
The version with ``TERM=vt100`` works fine with bash as well.

After init the original function works even with zsh, but at init time it needs the explicitly set ``TERM`` variable.