Tweak layout in README.md installation markup.

Some code blocks weren't indented, so they ended up messing up the numbering. Indenting them fixed it.
Merge pull request #832 from craigcitro/patch-1

tweak layout in readme installation markup
Adding a new "hosted" plugin for running slides on various hosting platforms
updating README
updating README
Adding slide content for OpenShift hosting
Merge branch 'openshift-content' of github.com:ryanj/reveal.js