expanding parser for 'simple' dicts

Ready to merge.  This PR adds support for more complicated 'simple' dicts.  
```python
        But is it really simple?  Not quite.  The following substitutions are made:

        keys with dots ('.') will be split into dictionaries.
        booleans "True", "False" will be parsed
        numbers will be parsed as floats unless they begin with "0" or include one "." and end with "0"
        "{}" will be converted to {}
        "[]" will be converted to [] (that's "[ ]" with no space)

        For example, an entry in preload would be this:

        PARAMETERS.TXWAVESTATS: False,
        PARAMETERS.TXREALTIME: True,
        PARAMETERS.TXWAVEBURST: false,
        SCHEDULER.ACQUIRE_STATUS: {},
        SCHEDULER.CLOCK_SYNC: 48.2
        SCHEDULER.VERSION: 3.0

        which would translate back to
        { "PARAMETERS": { "TXWAVESTATS": False, "TXREALTIME": True, "TXWAVEBURST": "false" },
          "SCHEDULER": { "ACQUIRE_STATUS": { }, "CLOCK_SYNC", 48.2, "VERSION": "3.0"}
        }

```

In addition, startup_config is added to the preload sheet for InstrumentAgentInstance resources, imported as a "simple dict".