text: Title: Pymongo ssl parameter
  Body: #### Arctic Version
  
  1.43.0
  
  #### Arctic Store
  
  
  VersionStore
  
  
  #### Platform and version
  
  Python 3.5.2
  
  #### Description of problem and/or code sample that reproduces the issue
  
  In pymongo, we have the option to set ssl = True while connect to Mongo Cluster that requires ssl connection. However, in Arctic class, I cannot find this option while initialise an Arctic object. Did I miss anything or we should add ssl parameter(s) into Arctic initialisation? 
  
  
  