Syncher Tunnel Filters

[adam-26]

PR for #189 and #219.

To add a tunnel filter: LAZO.app.addTunnelFilter([tunnelFilter]);

Tunnel filter interface:

var tunnelFilter = {
    onRequest: function (method, modelOrArgs, params, options) {
        options.stop({ statusCode: 500, error: 'Something went wrong' });
        options.continue(method, modelOrArgs, params);
    },

    onSuccess: function (model, response, options) {
        options.stop(model, response);
        options.continue(model, response);
    },

    onError: function (model, response, options) {
        options.stop(model, response);
        options.continue(model, response);
    }
};

Instead of using the standard success() and error(), I opted to instead use continue() and stop() because I think it better shows the intent. Also, using success() and error() in the onSuccess() and onError() handlers was confusing.

When stop() is called in the onRequest() handler, the syncher request will not be processed. The tunnel filters onError() handlers will be executed.
When stop() is called in onSuccess()/onError() handlers, no more tunnel filters will be executed.

To understand the order the filters are processed, see this example:

var tunnelFilter1 = {
    onRequest: function (method, modelOrArgs, params, options) {
        LAZO.logger.info('onRequest1');
        options.continue(method, modelOrArgs, params);
    },

    onSuccess: function (model, response, options) {
        LAZO.logger.info('onSuccess1');
        options.continue(model, response);
    }
};

var tunnelFilter2 = {
    onRequest: function (method, modelOrArgs, params, options) {
        LAZO.logger.info('onRequest2');
        options.continue(method, modelOrArgs, params);
    },

    onSuccess: function (model, response, options) {
        LAZO.logger.info('onSuccess2');
        options.continue(model, response);
    }
};

LAZO.app.addTunnelFilter(tunnelFilter1);
LAZO.app.addTunnelFilter(tunnelFilter2);

// onRequest1
// onRequest2
// [Syncher function executed here]
// onSuccess2
// onSuccess1

Let me know if you have any questions. Adam.