text: Title: Rename resp.body to resp.text
  Body: For both the WSGI and ASGI interfaces, rename Response.body to Response.text to provide a better contrast to Response.data. Response.body should then be made a deprecated alias.
  
  Don't forget to also grep the docstrings and /docs for references to 'body' and update them accordingly.
  
  NOTE: It may be best to wait to implement this issue until #1573 is merged to avoid conflicts.