Make the script work on other computers

Achieve it by adding and sourcing configuration file
with the name extension ".conf"
located in the same directory.
The configuration file is intended to be customized
by user to match his backup requirements.
But exclude the current customized configuration file
from git version controlling. Include only template of it
with the name extension ".conf.template" .
Currently there are 3 values
customizable by the configuration file:
date format, time format and directory
where a special subdirectory will be created.

 # On branch make-it-work-on-other-machines
 # Your branch is up-to-date with 'master'.
 #
 # Changes to be committed:
 #	modified:   .gitignore
 #	modified:   backup-script-tar-bz2.sh
 #	new file:   backup-script-tar-bz2.sh.conf.template
 #