- hooked ssl and ssl_letsencrypt checkboxes

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

Added sone lines to rmeoting api description file for dns (I hope thats correct...)

This one also sets type SPF as well as two records within DNS as of RFC4408
Hop that's okay?

This is a considered as stable stable release. (tested the workflow successfully)
Note: I am not perfect at RegEx I know the RegEx for LOC- and DS-Records is actually not checking. The DS-Regex is definitely valid (tested on regexpal).
Along with my dns-status modification this should not be a problem at all.

And found a small bug (privkeys were not deleted on zone deletion) which is now fixed
Testing successful. Doing last test then if everything goes well this will be the new merge request