Made some changes to the README.md

I've made some changes to README.md

* Remove references to Heroku, closes #80
  I really think we should not support Heroku
* Remove long lines in README.md using vim "gqip"
  I think it's a lot easier to read short lines
* Add robohash to license section
  Not sure about this one. Maybe we should list all of our dependencies and their licenses..?
* Replace "morbo" with "daemon" in "Running convos in production"
  I don't think the end user need to know about "morbo". It's more useful to show "daemon" imo.
* Remove "Running the backend separately."
  This is not required anymore
* Add install steps using git
  I think this is the simplest way to always have the latest version in an isolated environment (I considered adding "git checkout release", what do you think?)
I wonder if we should flip this around to advocate checking out from git, and having the script as a fallback. Git checkouts have much easier upgrades.