v2.6.0

Added:

• [dnsprovider] Add support for Joker.com DMAPI
• [dnsprovider] Add support for Bindman DNS provider
• [dnsprovider] Add support for EasyDNS
• [lib] Get an existing certificate by URL

Changed:

• [dnsprovider] digitalocean: LEGO_EXPERIMENTAL_CNAME_SUPPORT support
• [dnsprovider] gcloud: Use fqdn to get zone Present/CleanUp
• [dnsprovider] exec: serial behavior
• [dnsprovider] manual: serial behavior.
• [dnsprovider] Strip newlines when reading environment variables from _FILE suffixed files.

Fixed:

• [cli] fix: cli disable-cp option.
• [dnsprovider] gcloud: fix zone visibility.