Exposing pagination information from API

-- Added properties to Response object: page, next_page, prev_page, results_per_page, total_page, total_results_size, results_size
-- Added methods in SearchForm:
  - page(pageNumber) : for querying a specific page
  - pageSize(size) : for querying with a specific number of results per page
  - count : for counting the total number of results
-- Added tests