A little more unit testing.

Added the backrefs parameter to the lineinfile module.
Added tests for the backrefs functionality of the lineinfile module.

Both modules seboolean and zfs have not been adapted since they defer from the default (either by having a 'null' or special state, or prefering "on"/"off" for state indication.

Fixed duplicate call for file attributes checking

Added path expanding for dest in lineinfile
Added common file arguments to lineinfile so the module gets owner,
group, mode and SE options.
Decorated existing example to demonstate usage of file options and added
a couple more examples
Message is not set accordingly when file attributes were changed
'absent' handling code now handles the case where the file doesn't
exists (was issuing a Traceback before)
File attribute handling code has been added to the 'absent' handling
function too.
File attributes handling has been grouped in 'def check_file' since it's
required in both places.
'absent' mode now returns a message like it's counterpart 'present',
telling if file attributes were altered and if lines have matched.

a colon, which needs some special attention.

fix case in which file is created and backup is requested but fails, not it just doesn't attempt to backup the missing file
Signed-off-by: Brian Coca <briancoca+ansible@gmail.com>

We use the lineinfile module to modify configuration files of a proprietary application. This application reads configuration options from files, but does not require those files to exist (if the default options are fine). However this application may modify the configuration file at will, so we cannot copy or template those files. And after a silent install the configuration may not exist (depending on the response file).

Whatever the case, during deployment we need to make sure some configuration options are set after the installation.

So the cleanest way to handle this situation is to allow the lineinfile module to create the file if it is missing (and this is the expected behavior). When I proposed this behavior, @sergevanginderachter needed the same functionality and was now working around it as well.

 - added terse syntax to modules.rst
 - added description of special variables to template module

Various tweaking to get the module formatter to work for 'make docs' in the docs project.  Likely the templates for other module formatting types will have to change
by the time I'm done.