ChangeLog 2.5 updates
bump version to 2.5, minor fwknopd -S exit status update

This commit bumps the fwknop version to 2.5 and sets the libfko version to 2.0 to
signal incompatibility with older libfko versions.  Backwards compatibility is
maintained in SPA packet construction, but function prototypes in libfko-2.0 are
no longer compatible with older versions.

This commit also returns non-zero exit status under 'fwknopd --status' if there
is no existing fwknopd process.  This is better than always exiting with a zero
status regardless of whether fwknopd is already running or not, and adds a level
of scriptability to --status usage.  This change was suggested by George Herlin.
bumped VERSION file to fwknop-2.5
[test suite] bug fix for rotate digest cache tests

When the test suite is executed with '--include "rotate"' then previous tests
aren't executed in order to create a new digest cache file.  So, when init() is
called and a clean slate is established, there is nothing to rotate away.  This
change creates the default digest cache data (comment line only) if the file
doesn't already exist for the rotate tests.
Interim commit to add a VERBOSE variable to fwknopd.
Fixed use of --verbose command line switch.

Set default log verbosity to LOG_INFO in the log_msg driver.
s/VERBOSITY/VERBOSE/g on the server side for consistency purposes.
* Mentionned the VERBOSE variable in fwknopd.conf.
* Made sure the -v command line switch overrides the value of the
  VERBOSE variable set in an fwknopd.conf file.