(maint) Fix unescaped '\' character in doc comment.

Fixing unescaped '\' character in doc comment.

This was causing doxygen to treat it as a command.
(CFACT-145) Replace trace command line option with log-level.

Replacing the trace command line option with a more generic log-level
option that allows the user to set the output logging to trace, debug,
info, warn, error, or fatal.

The trace command line option is going to be re-implemented as the same
option used by Ruby Facter: logging Ruby stack traces.  This will make
the --trace option backwards compatible and make it integrate more
easily with Puppet.
(CFACT-145) Implement trace command line option.

Implementing the trace command line option to mean "log ruby exceptions
with stack traces" like it does in Ruby Facter.

This also adds the methods Facter.trace and Facter.trace? to the cfacter
Ruby API.
(CFACT-145) Implement Facter.debugging and Facter.on_message.

Implementing Facter.debugging and Facter.on_message in the Ruby API.
This enables logged messages to be intercepted by clients like Puppet.

Adding the "none" log level that disables log output.

Adding --color and --no-color options to control cfacter's log coloring.

This commit also silences the noisy output (and often confusing) log
output during unit testing.
Merge pull request #229 from peterhuene/cfact/145

(CFACT-145) Implement Ruby API looking hooks for client applications like Puppet.

* peterhuene-cfact/145
  (CFACT-145) Implement Facter.debugging and Facter.on_message.
  (CFACT-145) Implement trace command line option.
  (CFACT-145) Replace trace command line option with log-level.
  (maint) Fix unescaped '\' character in doc comment.