To use command line config-tool to configure ckan IC / PC

[skrchnavy]

in ckan/ckan#1804 there was request to allow editing config file for ckan without sed.
Result is in https://github.com/ckan/ckan/pull/1881/files

examples of usage in CKAN 2.3.2: https://github.com/ckan/ckan/blob/ckan-2.3.2/ckan/lib/cli.py#L2536

So it shall be possible to configure also our production.ini files without sed in postinst scripts and also to remove settings in rollback