This change fixes the output 'module_args' information of the plugins
'merge_configs' and 'merge_yaml' when Ansible is executed in maximum
verbose mode. Now all the plugin options are displayed instead of
standard 'copy' plugin options only.

Also, this change contains fixes already applied in the Kayobe
project to improve and synchronize the code of the plugins between
projects.

Change-Id: Ie2d9a0501fe29bfd854eb31258f282b197855948
Signed-off-by: Maksim Malchuk <maksim.malchuk@gmail.com>