Define clients data structure

[oubiwann]

There will be four client data structures we need to define:

• Base client data
• Scheduler client data
• Executor client data
• Operator client data

Each of the latter three will differ based upon the individual APIs they represent, with the first one defining all the data common to the rest.

The client data that will be used by the library functions will need to have the following defined for it:

• [x] base url
• [x] version
• [x] function for building base url + version
• [x] command connection
• [x] event/subscription connection
• [x] options (some of which might get passed on to clj-http)
• client-specific data
  • [x] base client
  • [x] scheduler
  • [ ] executor
  • [ ] operator

Probably just start simply with a record with a few fields and some protocols with a few methods, and add more later as needed.

[oubiwann]

Even though the last two are not done yet, the spirit of this ticket has been completed.