Add installation instructions for Ubuntu to README

[JavaJens]

Hey,

I added some needed dependencies for Ubuntu to the README. I hope the way I did this is correct. This is my first pull request.

Thanks

[grawity]

Some comments:

• Since commits 2-5 only make minor updates to the first one, all five of them should be squashed into a single commit, in order to keep the history cleaner. See intro to rebase for some more information.

  Run git rebase -i origin/master, then use the fixup or squash actions. When done, push again to the same branch with git push --force ....

• Some commits have the author stored as "jab@kiki.(none)" instead of your real email address. Tell git your name and email with:

  git config --global user.name "Your Name"
  git config --global user.email "you@example.com"

• When editing a document, follow the formatting style it uses; for example, in the current README.md all headers are separated from text with blank lines:

  # Installation
  
  ## Installation on Ubuntu
  
  In order for it to properly install...