Improve logging function

[nnance]

Take a more TypeScript approach to logging

export enum LogAction {
request, parse, validation, execute
}

export enum LogStep {
start, end
}

export interface LogMessage {
action: LogAction;
step: LogStep;
data?: Object;
}

export interface LogFunction {
(message: LogMessage);
}

export interface QueryOptions {
...
logFunction?: LogFunction;
...
}

Then use it like this:
logFunction({action: LogAction.request, step: LogStep.start});

This is more verbose but avoids string matching / parsing and makes it much easier for the consumer.