Copyedit on Moving to Git and GitHub use cases

- Some 301s or 404 on Testimonials
- Remove reference to Delicious bookmarks
- Italicise questions in Q&A to avoid the odd formatting of bullets
  floating in the air
- Justifications was linking to same page for different reasons
Merge pull request #191 from randomecho/usecases-moving-to-git-copyedit

Copy edits on Moving to Git and GitHub use cases, link corrections/updates