Proposed fix for #3929 (letsencrypt can not be activated when a new website gets created). Needs testing.

- Changed default value for expire of ftp user, should have fixed: #3862

Removed hard-coded suffixes because it gets dynamically added by "$app->functions->formatBytes($tmp_rec['t']);".

- fixed missing language file entries

Fixed: Issue #3820 v3.1 Shell user wrong default Base Dir in GUI results to corrupt shell user home directory creation.

- hooked ssl and ssl_letsencrypt checkboxes

- added limit for letsencrypt and directive snippets selector to client limits
- hide ssl tab if letsencrypt is selected