Basic integration of new v3 API endpoints and query paging

- Add new Endpoints event-counts, aggregate-event-counts, server-time can be requested using _query method

- Add new parameters summarize_by, count_by, count_filter added for event-counts and aggregate-event-counts

- Add support for include-total to fetch total number of results

- Add basic query paging support to _query method with parameters: order_by, limit, offset

- Add wrapper api methods for event_counts, aggregate_event_counts, server_time
fix for pep8 style check
Merge pull request #17 from juliushaertl/feature-v3-newapis

Basic integration of new v3 API endpoints and query paging