Modified enable-alarm to install a crontab that runs tea-break.sh at the
start of every hour.

This feature is very bare bones at present; there is no mechanism to
preserve, or even append to any existing crontab. If the user had existing
cron jobs installed in their crontab, they will be lost.

disable-alarm simply clears the crontab, replacing the tea-break job with
an empty crontab.
Changed path to tea-break.sh in enable-alarm to point to /usr/local/share
rather than /usr/local/lib.