v1.13

Bug fixed:

• #634 The container did not work with Buypass Go SSL (#637)

Changes since v1.12.1:

• Ability to request multiple single domain certificates instead of a SAN certificate (#647)
• Ability to create standalone certificates from a config file instead of a container env vars (#654)
• Upgraded base image to alpine 3.11 and docker-gen build stage to go 1.14 (#628)

Other changes:

• Documentation updates and corrections. (#626 #640 #657)
• Various test suite updates (#632)
• Some code linting (#641)