change Remove by RemoveName to fix DeleteRecords not working

[mcarbonneaux]

after the issue: #1

i've tested replacing Remove by RemoveName and is working fine (i use bind as dns server).

this example work fine (we need to specify Type record with Name, without that we crash on RemoveName because rr is nil).

// delete records 
deletedRecs, err := provider.DeleteRecords(ctx, zone, []libdns.Record{
{
	Name: "sub",
	Type: "A",
},
})

[mholt]

@mcarbonneaux Let me know if you don't hear from @KoHcoJlb soon -- then ping me, and I assume your change is a good fix and will merge it.

[conblem]

In that case could this be merged now?

[mholt]

I just noticed that the implementation by @emersion (which is nearly identical to this repo, oops -- we're working on addressing that soon) uses Remove():

https://github.com/libdns/dnsupdate/blob/2e79c50ea2ee12b484ae312b13e4ac81ffe78623/provider.go#L135

Are we sure that deleting all the RRSets is right?

[KoHcoJlb]

I've also checked this today.
RemoveName would remove all records with the same name, which I believe is non intended usage of the interface.
Separate method could be added for this, or just simple Get-Filter-Delete)