Activity input/output recording

[rebelzach]

• When execution starts create a model for json file, the file should be named with a "run" timestamp. Later these runs can be compared.
• When an activity starts
  • Write the input state as a dictionary entry in the model
    • Serialized input options
    • Hash of the activity input state
      • Activity code version
      • Serialized input options
      • Hash of the file system state
• After running
  • store serialized outputs
  • store hash of file system when it ends.