General code cleanup.

Remove unused function isIPv6.

Remove unused structure.

Fix definition of HostProperties structure.

Move PrintList function to public header.

Remove unused definitions of functions.

Replace printf functions with CfOut.

Fix indentation.

Remove error string from CfOut messages.

Remove unused variable 'tried'.

Change output type from cf_inform to cf_reporting.

Code cleanup.

Use ListIteratorData instead of direct dereferencing if iterators.
Search for env variable to find avahi library.

If avahi is installed in non-standard location use env variable
AVAHI_PATH to specify location of libraries i.e.:

AVAHI_PATH=/lib/libavahi-client.so ./cf-agent -B

If not specified cf-agent will look for libraries in default locations.
Add unit test for automatic bootstrap.

Test cases covered:

1. No hubs found.
2. One hub found.
3. Multiple hubs found.
4. Avahi error occured.