* Fixing wrong function calls leading to error 500.
* Merging enable/disabling/status into single action, to improve
handling in cli, and reduce code duplication.
* Fixing order of restart and enabling of public registration option.
* Minor, cosmetic fixes of code and user-facing strings.
* Overall code design now almost identical to Ejabberd service page.
Signed-off-by: Johannes Keyser <johanneskeyser@posteo.de>