Load more than 20 records to work around big zones

[aklinkert]

Following the comment of @awkwardbunny : https://github.com/tunix/digitalocean-dyndns/pull/6#discussion_r432910927

Fixes #7 Closes #6

[tunix]

@aklinkert thanks for your contribution!

[aklinkert]

You're welcome and thank you for merging 👋