Add date ranges and content custom filters to the getleadactivity api

Currently, when you extract the lead activities though the API, you have no choice: it's an all or nothing since the only parameter you can filter on is the activity type.

It would save a lot of time, network bandwidth, server resources and API daily quota if we could restrict the activities:

• With date ranges (time would be event better)
• with filters on fields that are relevant to the activity itself. For instance, on a data value change, I would love to be able to restrict on source or attribute, while on form fill outs, I would like to restrict on form name or ID.

-Greg