Added remote footer functionality

The remote footer support is a workaround for the fact that
ONA still isn't capable of handling external references
in terms of DNS records.

Remote footers can be enabled by using the option "-t".
For each domain on the name server the build_bind script
will check for an available footer file on a web server.
Instructions are included with the README file.
Implemented external configuration file including config template.

fixes opennetadmin/build_bind#3
fixed some comments in the template config file
fixed some glitches within the README file
Merge pull request #10 from FoundationUniversity/master

Added remote footer functionality and new build_bind.conf config file.