Add support for adding a manual CAA record

[yodax]

For #1154 and discourse topic

This PR allows a user to add a CAA record manually.

This results in:

dig @ns1.box.test.domain test.domain CAA

; <<>> DiG 9.11.0-P3 <<>> @ns1.box.test.domain test.domain CAA
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 18331
;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 5
;; WARNING: recursion requested but not available

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;test.domain.			IN	CAA

;; ANSWER SECTION:
test.domain.		1800	IN	CAA	0 issuewild "letsencrypt.org"

;; AUTHORITY SECTION:
test.domain.		1800	IN	NS	ns1.box.test.domain.
test.domain.		1800	IN	NS	ns2.box.test.domain.

;; ADDITIONAL SECTION:
ns1.box.test.domain.	1800	IN	A	xx
ns2.box.test.domain.	1800	IN	A	xx
ns1.box.test.domain.	1800	IN	AAAA	xx
ns2.box.test.domain.	1800	IN	AAAA	xx

;; Query time: 24 msec
;; SERVER: xx#53(xx)
;; WHEN: Wed Apr 12 14:24:28 CEST 2017
;; MSG SIZE  rcvd: 206

Maybe in the future we could make this automatic when we request certificates from lets encrypt.

[JoshData]

There's an extra "or".

[yodax]

Thanks 😄

[kimusan]

Would it be possible to get them automatically added to the ones automatically created by miab (the letsencrypt ones)?

[yodax]

@kimusan Thanks for the reply, would you mind creating a separate issue for it? That allows for better tracking 😄