text: Title: Add support for the Parsel JMESPath feature
  Body: See https://github.com/scrapy/parsel/pull/181 and https://github.com/Gallaecio/scrapy/commit/d642881e25b6a7ce7d8f640b354459b9a4921790 linked there.
  
  Note that the minimum version of Parsel that Scrapy requires should stay the same, i.e. no need to update the minimum version of Parsel in setup.py. 