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 agree. I was actually thinking about making an issue where we change install.sh to check if "git" is available. If it is, it will use git instead of fetching the tar.gz. Could you make the issue to me, if you think it's a good idea?