code cleaned up
Threshold set back to 20 percent
Added hibernation message to log
Added log messages
Added timestamp to log entries
Changed hibernate command to be full path
Added -v to remove command of INSTALL file
Made AfterHibernation function run only if BeforeHibernation function ran
DEVELOPER_NOTES.rst file added
Made on-battery check more important than percent check

There was a problem with the original code, where I accidentally
made it always check for percent the battery was at until it
reached the threshold, and only then checked if it's still on
battery power. This made it so that if power was restored to the
UPS before it reached the threshold, the script would keep running,
waiting until it reached the threshold. This fixes the problem.
Added an idea to DEVELOPER_NOTES file
Added note to DEV_NOTES file
Added notes to DEV_NOTES
"no script currently running" line commented out
"UPS is on battery" line removed
DEV_NOTES updated
Switched back to pm-hibernate
Updated DEV_NOTES
Added check to make sure script is not run directly (without cron)
Added check to see if script being run as root, and changed INSTALL.rst file accordingly