Rewrite the scc Readme

- Improve the description of the installation procedure
- List the dependencies in a separate section
- Write an extended section describing the test suite and their requirements
Closes #99
Fix markup
merge master -D org -I include -E exclude: PR 108 (Improve scc unrebased-prs output)
merge master -D org -I include -E exclude: PR 109 (Rewrite readme)