spark.jobserver.util
creates SSLContext based on configuration, the SSLContext is used for communication between the SJS web server and its clients
if encryption is not activated in the configuration, then the default ssl context is used which falls back to un-encrypted communication
based on https://github.com/spray/spray/blob/v1.2-M8/examples/ spray-can/simple-http-server/src/main/scala/spray/examples/MySslConfiguration.scala
creates SSLContext based on configuration, the SSLContext is used for communication between the SJS web server and its clients
if encryption is not activated in the configuration, then the default ssl context is used which falls back to un-encrypted communication