RETURN_PARAMS JSON format may be incorrect

[ellerychan]

@jaron42: Please confirm this and I will fix:

The current RETURN_PARAMS value in the Setting table (as shown in the _MSSettings.xlsx document) is an array with one entry for each station, but it should be a dict indexed by _stationid.

I think it should really be this:

{
   "return01": [1, 2, 3, 4, 5, 6],
   "return02": [1, 2, 3, 4, 5, 6],
   ...
   "return06": [1, 2, 3, 4, 5, 6]
}

The doc string in Setting.getReturnParams() (in dbkeeper/models.py) will need to be updated to reflect the new format, but the code should not need modification. With the format shown in the _MSSettings.xlsx and documented in the code, it should not work correctly.

[ellerychan]

Addressed in Pull Request #86.