camelCase Timer Trigger object

[mhoeger]

In V1, the timer trigger object looked something like this:

{
    isPastDue: bool,
    next: string, // time
    last: string // time
}

In V2, the timer trigger object looks something like this:

{
    IsPastDue: bool,
    Schedule: { ... }
    ScheduleStatus: {
        "Last": string, // time
        "LastUpdated": string, //time
        "Next": string // time
    }
}

In 3.x, we should be sure to camelCase the properties and hopefully address this todo: https://github.com/Azure/azure-functions-host/blob/v1.x/src/WebJobs.Script/Description/Node/NodeFunctionInvoker.cs#L408

In V3:

{
    isPastDue: bool,
    schedule: { ... }
    scheduleStatus: {
        "last": string, // time
        "lastUpdated": string, //time
        "next": string // time
    }
}

TODO: Need to generalize this model rather than hardcode so other extensions can also express their Node.js object model