Actions now yield (RequestT, ResponseT)

These two named tuples allow for more structured responses (as opposed
to returning just the curl string as before). This will be useful in
remembering last request / response so that they can be edited using
vim, which functionality is coming up.
Somewhat working vim edit

This feature allows users to edit their queries in vim without exiting
elsec, for easy iteration.
Updated README
Version bump to 0.9.2
Merge branch 'dev' into vim
Added 'edit' command, request history

'edit' command allows you to edit the most recent request using VIM, and
to re-run it. The most recent request is now stored on exit and read on
startup, and when you run 'search' and 'count' without any parameters,
this most recent request gets executed. All this functionality is now
documented and part of the TUTORIAL.md

Version bumped to 0.9.3
Updated README.md
Updated changelog