Adding parameter: startupTimeout

This fixes Issue #6, in which the backup failed because it took more than the hardcoded time for the second copy of the database to fully start up. I added the new parameter to the configuration file, and modified the code to respect the parameter, in the loop where it waits for the DB to start

v0.3

This incorporates some documentation updates, and I changed one instance systemctl start mariadb into calling a function.