Allow Connections to Remote Docker via secured TLS

[Nanabell]

With this the agent can connect to docker system that use Certificates to expose a secured TLS Connection, so you don't need to expose an unprotected Docker system.

Added a new section to the application.yml file

  ssl:

    # type of SSL configuration. Can be 'NONE', 'KEYSTORE' or 'PEM_FILES'
    # Setting this to none disables SSL configuration
    type: none

    keystore-file:                        # Path to either a .jks or .pkcs12 file.
    keystore-pass:                        # Password for the keystore or pkcs12 file.

    # Path to a directory containing a ca.pem, key.pem & cert.pem
    # These files must be named and have the file extension as described above!
    pem-directory:

Currently only PEM_FILES support is implemented, there should be little reason for people to use a Keystore since it would require the pem files in the first place.

Official guide how to create the certificates: https://docs.docker.com/engine/security/https/
closes #4

As a little bonus allows to set

  orchestrator:
    enabled: false

to disable orchestrator without having to remove configuration