Add support for self-signed certificates

[shwill]

Issue

If you are using self-signed certificates with a custom CA in your organisation, you need to supply the trusted root files to the trusted root CA store within alpine linux in order to make an SSL-encrypted connection.

Disabling certificate verification with VSPHERE_IGNORE_SSL=TRUE is not viable in production environments.

Solution

Add the trusted root certificates to the alpine linux trusted root store.

Changes

• Added a certs directory, containing all required certificates of the chain split into individual files in PEM format
• Added documentation to certs/README.md to not push an empty directory. Added this readme to the .dockerignore file
• Updated Dockerfile to COPY all files within the certs-folder to /usr/local/share/ca-certificates/
• Updated Dockerfile to install the certificates by executing update-ca-certificates