Proposed fixes for issue #225 and #247 (search() uses V1 API)

Please review and comment.  This works in my limited testing, but I cannot run the full test suite in my environment. 

- search() fix path (URL) to use 1.1 API url
 - search() allowed_param changes: rpp -> count, adding include_entities
 - search_api flag no longer needed or used.
 - SearchResults class: Pull list results from ['statuses'], use
  parse_datetime() rather than parse_search_datetime() since the date
  format is now standardized.
 - utils.parse_search_datetime() no longer used and has been deleted.