Refactor loadSensorDataFromDb()to use sqlite prepare
Refactor loadSensorDataFromDb()to use sqlite prepare

Breaking API changes values are returned as:

[
    {
        "state/lightlevel": 18458,
        "t": "2018-06-22T13:39:09"
    },...
]

dresden-elektronik/deconz-rest-plugin,dresden-elektronik/deconz-rest-plugin,dresden-elektronik/deconz-rest-plugin,dresden-elektronik/deconz-rest-plugin,dresden-elektronik/deconz-rest-plugin